Summary
Sea sponges live on the ocean floor and feed by filtering water. Two sponge types (tubular sponges and vase-shaped sponges) can filter feed without help from the current, so they do well in quiet waters. They also can’t live in stronger currents, because they would be dislodged from the ocean floor. Finally, both tubular and vase-shaped sponges were widespread in the late Jurassic period.
Strongly Supported Conclusions
These facts strongly support the conclusion that the late Jurassic period had many areas of ocean floor with slow currents, thus allowing tubular and vase-shaped sponges to be widespread. They also support the conclusion that areas with slow currents can still have enough fresh water moving through for sponges to find food.
A
Few tubular or vase-shaped sponges lived before the late Jurassic period.
Like (B), this is not supported. The only period covered by the stimulus is the late Jurassic: we don’t know what conditions were like for sponges, or how many sponges were around, either before or after.
B
Tubular and vase-shaped sponges were more common during the late Jurassic period than in succeeding geological eras.
Like (A), this is not supported. Because the facts only apply to the late Jurassic period, we can’t draw any conclusions about other periods, either before or after.
C
During the late Jurassic period there were many areas of the ocean floor where currents were weak.
This is strongly supported. The facts tell us that tubular and vase-shaped sponges can only live on the ocean floor where the current is weak. So, for them to be widespread during the late Jurassic period, there had to be widespread areas of the ocean floor with weak currents.
D
All sponges that are neither tubular nor vase-shaped inhabit areas of the ocean floor where there are extremely strong currents.
This is not supported. The author only discusses tubular and vase-shaped sponges; we learn nothing about other kinds of sponges. We don’t even know if there are other sponges, let alone what environmental conditions they prefer.
E
No types of sponge live in large colonies, since sponges do not flourish in areas where much of the water has been filtered by other sponges.
This is not supported. The stimulus doesn’t directly discuss sponge colonies, and we also cannot infer this from what we do know. We just don’t have enough detail about sponges’ filter feeding to know whether a sponge in a colony could still access enough food to flourish.
"Surprising" Phenomenon
What caused modern tree-dwelling kangaroos to lose traits of their ancestors that were well-suited for life in trees?
Objective
The right answer will be a hypothesis that offers a similarity between land- and tree-dwelling kangaroos. This similarity will explain why modern tree-dwelling kangaroos, like their land-dwelling counterparts, lost the prehensile tails and opposable thumbs of their ancestors, even though these traits are well-adapted to tree-dwelling kangaroos’ lifestyles.
A
Modern tree-dwelling kangaroos must back down tree trunks slowly and carefully, but the common ancestors of modern tree- and land-dwelling kangaroos used their opposable thumbs to descend trees quickly headfirst.
This does not help explain the puzzling fact. (A) says that modern tree-dwelling kangaroos must descend tree trunks more slowly than their ancestors, presumably because they lack opposable thumbs, without explaining why they lost this trait.
B
Modern tree-dwelling kangaroos are smaller than most modern land-dwelling kangaroos but larger than their common ancestors.
This does not help explain the puzzling fact. (B) discusses size, which is not one of the traits the stimulus discusses as being beneficial for a tree-dwelling lifestyle. Furthermore, (B) offers a difference between land- and tree- dwelling kangaroos, not a similarity.
C
Modern tree-dwelling kangaroos’ tails cannot grasp branches, but they are somewhat longer and more flexible than those of modern land-dwelling kangaroos.
(C) offers a difference between land- and tree- dwelling kangaroos, not a similarity. The difference in length and flexibility of the kangaroos’ tails is not helpful for explaining the puzzling fact in the stimulus.
D
Modern tree-dwelling kangaroos are descended from species of land-dwelling kangaroos that had been land-dwellers for many generations before modern tree-dwelling kangaroos started to develop.
(D) says modern land- and tree-dwelling kangaroos share a similarity: in addition to sharing a common ancestor, they both evolved from land-dwelling kangaroos. This explains why modern tree-dwelling kangaroos lost some of their earlier ancestor’s beneficial tree-dwelling traits.
E
Modern tree-dwelling kangaroos have smaller and weaker hind legs than modern land-dwelling kangaroos, and they move more slowly on land than do modern land-dwelling kangaroos.
(E) offers a difference between land- and tree- dwelling kangaroos, not a similarity. The difference in the size and strength of the kangaroos’ hind legs is not helpful for explaining the puzzling fact in the stimulus.
Summarize Argument
The author concludes that the North American Free Trade Agreement is misnamed. As evidence, the author points to the principles outlined by Adam Smith which describe any obstacle placed in the way of free movement of goods, investment, or labor defeats free trade. Moreover, since under the agreement workers would be restricted by national boundaries, the North American Free Trade Agreement would not truly result in free trade.
Describe Method of Reasoning
The author criticizes the North American Free Trade Agreement as being misnamed because of the restrictions the agreement would place on workers. He does this by appealing to economist Adam Smith, whose principles of free trade are in contrast with what the agreement entails.
A
ruling out alternatives
The author does not rule out any alternatives. The author’s argument is limited specifically to the North American Free Trade Agreement, no other agreements or acts are mentioned.
B
using a term in two different senses
The author concludes that the North American Free Trade Agreement is misnamed, but the author himself does not use the term “free trade” in two different senses.
C
citing a nonrepresentative instance
The author does not cite a nonrepresentative instance. The author’s argument is restricted specifically to the North American Free Trade Agreement.
D
appealing to a relevant authority
The authority is the economist Adam Smith. He is a relevant authority because he is the economist who first articulated the principles of free trade.
E
responding to a different issue from the one posed
The author does not respond to a different issue. The issue is the misnaming of the North American Free Trade Agreement and the author never strays away from addressing this issue.
Summarize Argument: Phenomenon-Hypothesis
In households that regularly used for the past several years an insect trap consisting of pesticide mixed with glucose, the trap is much less effective today. The author hypothesizes that this is because successive generations of insects developed a resistance to the pesticide in the traps.
Notable Assumptions
The author assumes there isn’t another cause for the decreased effectiveness of the traps.
A
In households where the traps have been used regularly, the proportion of insect pests that have a natural aversion to eating glucose has increased with each successive generation.
This provides an alternate explanation for the decreased effectiveness of the traps. The glucose in the trap is not as attractive anymore, which means fewer insects enter the traps. This results in decreased effectiveness, even if the insects aren’t resistant to the pesticide.
B
Even when only a few individuals out of an entire generation of insects survive the effects of a pesticide, the offspring of those individuals are usually resistant to that pesticide.
If anything, this answer supports the author’s theory by showing resistance can develop in offspring even if one generation is almost entirely wiped out.
C
After eating glucose mixed with the pesticide, insects that live in households that do not use the trap tend to die in greater numbers than do insects from households where the traps have been used regularly.
If anything, this could support the author’s theory by showing that in households where insects haven’t had the chance to build up resistance, the trap is more effective than in households that have used the trap for several years.
D
After the manufacturer of the traps increased the concentration of the pesticide used in the traps, the traps were no more effective in eliminating household insect pests than were the original traps.
This is consistent with the author’s hypothesis. Increased concentration of the pesticide should make the trap more effective. Just because the traps didn’t become more effective than the original doesn’t mean they didn’t become more effective.
E
The kind of glucose used to bait the traps is one of several different kinds of glucose that occur naturally.
The fact the glucose occurs naturally doesn’t have any impact. Does natural glucose have anything to do with the traps’ decreased effectiveness? We have no reason to think so.
Summarize Argument
The author thinks that the government should spend more on preventing chemical spills, rather than focusing primarily on cleaning them up. Why should we believe this? First, the current strategy is slow and is not keeping up with new spills; this shows us that something needs to change. Second, the author tells us that prevention is more effective than cleanup; this indicates what the change should be. Finally, we learn that the current annual spending on prevention is less than even one cleanup site costs per year; this highlights the urgency of the situation. All together, everything in the argument leads to the conclusion that we should spend more on prevention rather than cleanup.
Identify Argument Part
The claim about how the government’s budget should be redirected is the main conclusion of the argument.
A
It represents an unsupported speculation.
The proposal of redirecting the budget is not unsupported; in fact, everything else in the argument supports it.
B
It both supports another claim in the argument and is supported by others.
The proposal of redirecting the budget does not support anything else in the argument. It receives support, but it’s the main conclusion, so the support ends there.
C
It is the claim that the argument as a whole is structured to support.
This correctly describes that the proposal of redirecting the budget is the author’s main conclusion, and is supported by everything else in the argument.
D
It is a presupposition on which the argument is explicitly based.
The author never makes an explicit presupposition, so this wouldn’t be true of any part of the argument. Also, the claim about redirecting the budget is supported by other claims, not assumed (or presupposed).
E
It presents an objection to another proposal mentioned in the argument.
There is no other proposal mentioned in the argument. The author is arguing for a change from the current policy, but there are no competing views about what the change should be.
Hector: You may be right about what the sculpture’s popularity means about its artistic merit. However, a work of art that was commissioned for a public space ought to benefit the public, and popular opinion is ultimately the only way of determining what the public feels is to its benefit. Thus, if public opinion of this sculpture is what you say, then it certainly ought to be removed.
Summary
Hector concludes that, if Monica is correct that public opinion dislikes a recent public sculpture, then the sculpture should be removed. Why? Because public art should benefit the public, and public opinion is the only way to tell what the public feels is beneficial.
Notable Assumptions
Hector uses a measure of what the public feels about a sculpture to indicate the actual benefit of the sculpture. This depends on the assumption that when the public feels a sculpture is not beneficial, that indicates that the sculpture is truly not beneficial.
A
no matter what the public’s opinion is on an issue affecting the public good, that public opinion ought to be acted on, even though the opinion may not be a knowledgeable one
Hector’s argument is based on the idea that the public benefit should be pursued, and relies on equating what the public thinks is beneficial to what is truly beneficial. That’s possible even without following public opinion no matter what—this assumption is unnecessary.
B
Monica’s assessment of the public’s opinion of the sculpture is accurate
Hector’s conclusion is phrased as a conditional, so it doesn’t depend on whether Monica’s assessment is accurate. It just wouldn’t be triggered if Monica’s assessment is inaccurate.
C
if the sculpture had artistic merit, then even a public that was not knowledgeable about modern art would not scorn the sculpture
Hector isn’t concerned with the sculpture’s artistic merit, just whether it benefits the public. That makes this, like (D), both unnecessary and irrelevant.
D
works of art commissioned for public spaces ought not to be expected to have artistic merit
Like (C), this is simply irrelevant, because Hector’s argument doesn’t involve whether or not the sculpture has artistic merit.
E
if the public feels that it does not benefit from the sculpture, this shows that the public does not in fact benefit from the sculpture
Hector infers that the public scorning the sculpture would mean the sculpture was not beneficial, on the basis that the public would not feel the sculpture was beneficial. This requires assuming that public feelings about the sculpture’s benefit actually indicate that benefit.
Summarize Argument
The author claims that the welfare state is not feasible. They explain this claim by saying that the welfare state rests on the false assumption that people are unselfish. We know that the welfare state rests on this assumption because it can only work if wage-earners will let their money be used to help those who need it more, which requires unselfishness. We know that the assumption of unselfishness is false because people innately focus on their own benefit, especially when that benefit is threatened by other people’s interests.
Identify Conclusion
The conclusion is the author’s assertion that the welfare state won’t work: “The welfare state cannot be successfully implemented.”
A
The welfare state will not work.
This accurately paraphrases the conclusion. Everything else in the argument supports the claim that the welfare state “cannot be successfully implemented,” meaning that it won’t work.
B
The welfare state unfairly asks those who work hard to help those in greater need.
The author does not claim that it is unfair to ask hard-working people to help others in greater need. According to the author, people may not want to help, but fairness is never mentioned.
C
The assumption that human beings are unselfish is false.
This is a sub-conclusion or major premise in the argument, not the main conclusion. This claim is supported by the statement that “people innately seek their own well-being”, but in turn this claim supports the main conclusion that the welfare state is not viable.
D
The interests of the less fortunate impinge on the interests of others.
This is not a claim the argument supports. The suggestion that some people’s interests may threaten other people’s interests emphasizes the claim that people are not selfish, but is not supported by anything else.
E
The welfare state relies on the generosity of wage earners.
This claim is not supported by the rest of the argument. Instead, it supports the idea that the welfare state requires people to be unselfish, which helps lead to the main conclusion.