Summarize Argument
The author concludes that changes in sea temperature that seem small will result in declining fish and seabird populations. This conclusion is supported by a description of a causal chain: a temperature increase of two degrees prevents the vertical mixing of seawater, which prevents phytoplankton from having access to nutrients. Zooplankton consume phytoplankton, so these zooplankton lose their food source, and the rest of the food chain is based on zooplankton. So the seemingly minor temperature increase results in a loss in food for the entire food chain.
Identify Argument Part
The statement in the question stem demonstrates how the loss of nutrients for phytoplankton impacts food sources for the broader food chain. (Zooplankton consume phytoplankton, and everything else relies on zooplankton for nutrients).
A
It is a hypothesis supported by the fact that phytoplankton feed on upwelling nutrients.
The fact that zooplankton consume phytoplankton does not receive support from any other part of the argument; it is a premise that we accept at face value. Further, it is not a hypothesis; it is a premise that supports the conclusion.
B
It is intended to provide an example of the ways in which the vertical mixing of seawater affects feeding habits.
The claim in the question stem is a description of a general relationship that is used as a premise. Also, it is not about the impact on feeding habits; it is about food access. The zooplankton would still eat phytoplankton if they were available.
C
It helps show how global temperature changes affect larger sea animals indirectly.
The statement in the question stem connects zooplankton to phytoplankton. This connection is a link in the causal chain that more broadly connects temperature increases to declining populations of fish and seabirds, showing how temperature changes affect sea animal populations.
D
It is offered as one reason that global warming must be curtailed.
There is no value judgement in the argument; the argument does not give any recommendations for action.
E
It is offered in support of the idea that global warming poses a threat to all organisms.
This argument shows how global warming poses a threat to fish and seabird populations, not to all organisms generally. This answer choice is too broad.
Summarize Argument: Phenomenon-Hypothesis
Some naturalists hypothesize that polar bears can navigate from unfamiliar territory to familiar areas across long distances. As support for this hypothesis, they reference a polar bear that returned home after it was released over 500 km away.
Notable Assumptions
The stimulus defines navigation as finding a way from an unfamiliar territory to familiar areas, but in the example of the polar bear, we don’t know if the polar bear was released in unfamiliar territory. The naturalists assume that the polar bear was released in unfamiliar territory. They also assume that the polar bear didn’t receive any other assistance in making its way home.
A
The polar bear stopped and changed course several times as it moved toward its home territory.
The fact that the polar bear changed course several times doesn’t contradict the fact that the polar bear successfully made it home after being released 500 km away.
B
The site at which the polar bear was released was on the bear’s annual migration route.
(B) weakens the argument because it shows that the polar bear did not meet one of the requirements of navigation: finding its way through unfamiliar territory. If the site at which the polar bear was released was familiar, then its actions don’t fit the definition of navigation.
C
The route along which the polar bear traveled consisted primarily of snow and drifting ice.
The terrain through which an animal is navigating is not relevant to the argument; we only care about if the polar bear was navigating.
D
Polar bears are only one of many species of mammal whose members have been known to find their way home from considerable distances.
It doesn’t matter how many animals are capable of finding their way home across long distances. We only care about if the example cited by the naturalists is aligned with the definition of navigation.
E
Polar bears often rely on their extreme sensitivity to smell in order to scent out familiar territory.
The argument is concerned with whether or not the polar bear was navigating, not how it was able to do so. The fact that polar bears often use smell is not relevant.
Smith: Granted, children’s interests are not always the same as their parents’; governmental deficits incurred by their parents’ generation will later affect their own generation’s standard of living. But even if children are told about the issues affecting them, which is not generally the case, their conceptions of what can or should be done are too simple, and their time horizons are radically different from those of adults, so we cannot give them the responsibility of voting.
Summarize Argument
Rossi claims that children should have the right to vote. To support this conclusion, Rossi states a principle that it is undemocratic for anyone to live under a government that doesn’t represent their interests. According to Rossi, children’s interests can differ from their parents’ interests—presumably making it undemocratic to ban children from voting.
Describe Method of Reasoning
Rossi’s argument starts with the general principle that it’s undemocratic not to represent citizens’ interests. Rossi then points out a particular case where that principle is violated: children’s interests aren’t always represented by their parents. Based on this, Rossi concludes that we should change our system so the principle is respected, by allowing children to vote.
A
It makes an appeal to a general principle.
Rossi appeals to the general principle that it’s undemocratic for a government not to represent the interests of all those living under it. The apparent violation of this principle leads to Rossi’s conclusion that children should get to vote.
B
It denies the good faith of an opponent.
Rossi doesn’t mention any opponents, and isn’t directly responding to another argument. There’s no issue of good faith here.
C
It relies on evaluating the predictable consequences of a proposal.
Rossi doesn’t address any predictable consequences of the proposal to allow children to vote (or of any other proposal).
D
It substitutes description for giving a rationale for a policy.
Rossi does give a rational for the proposed policy of allowing children to vote: that it would make society more democratic.
E
It employs a term on two different occasions in different senses.
There’s no term that Rossi uses to mean two different things on two different occasions. All the terms in Rossi’s argument appear to mean the same thing every time they’re used.
Summary
If you have no keyboarding skills, then you will not be able to use a computer. If you are not able to use a computer, then you will not be able to use a word processing program to write your essays.
Notable Valid Inferences
If you are able to use a word processing program to write your essays, then you have keyboarding skills.
A
If you have some keyboarding skills, you will be able to write your essays using a word processing program.
Could be false. We don’t have any conditional statements in the stimulus to tell us what occurs when a person does have keyboarding skills. Our first conditional statement tells us what occurs when a person does not have keyboarding skills.
B
If you are not able to write your essays using a word processing program, you have no keyboarding skills.
Could be false. We don’t have any conditional statements in the stimulus to tell us what occurs when a person is not able to use a word processing program. Not being able to use a word processing program is a necessary condition, it is not a sufficient condition.
C
If you are able to write your essays using a word processing program, you have at least some keyboarding skills.
Must be true. As shown below, this answer choice is the correct contrapositive of our conditional chain. 
D
If you are able to use a computer, you will probably be able to write your essays using a word processing program.
Could be false. The only statement we could infer if a person can use a computer is that that person has keyboarding skills. This answer choice is an incorrect contrapositive.
E
If you are not able to write your essays using a word processing program, you are not able to use a computer.
Could be false. We don’t have any conditional statements in the stimulus to tell us what occurs when a person is not able to use a word processing program. Not being able to use a word processing program is a necessary condition, it is not a sufficient condition.
Summarize Argument: Counter-Position
The author concludes that technologically advanced societies are threatened when the means of production are publicly owned. As support, the author claims that only private ownership of the means of production allows new technologies to be tested without the agreement of the group. The author disagrees with “some people” who believe that private ownership of the means of production is destructive for society.
Identify Argument Part
The claim in the question stem is the belief of “some people,” with whom the author of the argument disagrees.
A
It is a generalization that the argument suggests is no more applicable to less technologically advanced societies than to more technologically advanced societies.
The author actually claims that the proposition in the question stem may be applicable to less technologically advanced societies.
B
It is a hypothesis for whose widespread acceptance the argument offers an explanation.
We only know that “some people” hold the belief in the question stem; we do not know if it has widespread acceptance, and either way, its acceptance is not explained.
C
It is a general hypothesis that the argument suggests is inapplicable to societies more dependent for survival upon the introduction of new technologies than upon the sharing of resources.
The reason that the author gives for his disagreement with the proposition in the question stem is that it does not allow individuals to test new technologies; the author claims that the proposition in the question stem is dangerous for technologically advanced societies.
D
It is a contention about the consequences of an economic arrangement that the argument claims is incompatible with the needs of any society.
The author concedes that the claim in the question stem may be true of less technologically advanced societies; the author does not deem it incompatible with any society.
E
It is a generalization about societies that according to the argument is true for any society in which the majority of its citizens does not impede the introduction of new technologies.
The author argues that the proposition in the question stem is incompatible for technologically advanced societies; the author does not make any claims about societies in which the majority facilitates the introduction of new technologies.
Philosopher: The rational pursuit of happiness is quite different from always doing what one most strongly desires to do. This is because the rational pursuit of happiness must include consideration of long-term consequences, whereas our desires are usually focused on the short term. Moreover, desires are sometimes compulsions, and while ordinary desires result in at least momentary happiness when their goals are attained, compulsions strongly drive a person to pursue goals that offer no happiness even when reached.
Summary
The rational pursuit of happiness is different from doing what one strongly desires to do. The rational pursuit of happiness must include consideration of long-term consequences, whereas desires are usually focused on the short-term. Some desires are compulsions. While ordinary desires result in momentary happiness when their goals are attained, compulsions drive a person to pursue goals that offer no happiness even when reached.
Notable Valid Inferences
All desires result in happiness when their goals are reached.
A
The majority of people do not have compulsions.
Could be true. We don’t have any information in the stimulus about what most people experience. It is possible that most people do not have compulsions.
B
Attaining the goal of any desire results in momentary happiness.
Must be false. The stimulus tells us that some desires are compulsions, and compulsions result in no happiness. Therefore, it is impossible for any desire to result in momentary happiness.
C
Most people do not pursue happiness rationally.
Could be true. We don’t have any information in the stimulus about what most people experience. It is possible that most people do not rationally pursue happiness.
D
Most people want more than their own personal happiness.
Could be true. We don’t have any information in the stimulus about what most people experience. It is possible that most people desire more than personal happiness.
E
All actions have long-term consequences.
Could be true. We don’t have any information in the stimulus about what actions have what consequences. We only know that rational pursuit of happiness requires considering long-term consequences.