A
When webs of many different species of spider were illuminated with a uniform source of white light containing an ultraviolet component, many of these webs did not reflect the ultraviolet light.
Irrelevant. The author never said that Glomosus spiderwebs are the only spiderwebs that reflect ultraviolet light.
B
When the silks of spiders that spin silk only for lining burrows and covering eggs were illuminated with white light containing an ultraviolet component, the silks of these spiders reflected ultraviolet light.
Like (A), this is irrelevant. We don’t care about other spiderwebs that reflect ultraviolet light.
C
When webs of the comparatively recently evolved common garden spider were illuminated with white light containing an ultraviolet component, only certain portions of these webs reflected ultraviolet light.
Irrelevant. We don’t care about other spiderwebs that reflect ultraviolet light.
D
When Drosophila fruit flies were placed before a Glomosus web and a synthetic web of similar pattern that also reflected ultraviolet light and both webs were illuminated with white light containing an ultraviolet component, many of the fruit flies flew to the Glomosus web.
The author argues that the specific patterns of ultraviolet light attract insects. This suggests something else about the Glomosus spiderwebs is actually what attracts them.
E
When Drosophila fruit flies were placed before two Glomosus webs, one illuminated with white light containing an ultraviolet component and one illuminated with white light without an ultraviolet component, the majority flew to the ultraviolet reflecting web.
Between the otherwise identical Glomosus spiderwebs, insects chose the one with ultraviolet reflections. This strengthens the idea that ultraviolet reflections, and not something else about the spiderwebs, are what attract insects.
"Surprising" Phenomenon
Why do people who have reduced their consumption of red meat eat, on average, a lot more fat than those who haven’t reduced their consumption of red meat?
Objective
The correct answer will tell us something that allows us to differentiate people who have reduced red meat consumption from those who haven’t, and this difference will lead to greater fat consumption among the people who reduced red meat consumption.
A
Many more people have reduced their consumption of red meat over the last two decades than have not.
The number of people who have reduced red meat consumption has no bearing on the average fat intake of those people. We’re talking about group averages here; the number of people in the group has no effect.
B
Higher prices over the last two decades have done as much to decrease the consumption of red meat as health concerns have.
The cause of reduced red meat consumption has no impact on the average fat intake of people who eat less red meat.
C
People who reduce their consumption of red meat tend to consume as much of other foods that are high in fat as do those who have not reduced their consumption of red meat.
This could be correct if it had said people who reduce red meat consumption eat more high-fat foods than others. But it just says they eat “as much” as others. That doesn’t explain why their average fat intake is higher than that of those who haven’t reduced red meat consumption.
D
People who reduce their consumption of red meat tend to replace it with cheese and baked goods, which are richer in fat than red meat.
This shows why people who reduce consumption of red meat, on average, end up eating more fat. They replace red meat with stuff that has more fat. People who don’t reduce red meat consumption have nothing to replace, so they don’t eat as much of the other higher-fat foods.
E
Studies have shown that red meat contains slightly less fat than previously thought.
We’d still expect people who reduce red meat consumption to reduce their fat intake, even if the expected reduction isn’t as great as we initially thought.
Summarize Argument
The author concludes that fortifying salt with iron could help reduce the general incidence of anemia. People around the world consume enough salt that this advance would significantly increase their iron intake, thus remedying the iron deficiency that causes anemia.
Identify Argument Part
The referenced text supports the argument’s conclusion. Since people around the world eat enough salt for iron-fortified salt to make a health difference, iron-fortified salt could decrease the incidence of anemia brought on by iron deficiency.
A
It is the conclusion of the argument.
The author concludes that iron-fortified salt could help reduce the general instance of anemia. The reference text supports this conclusion.
B
It provides support for the conclusion of the argument.
The referenced text is a premise. It supports the conclusion by showing how salt is broadly-used and would therefore make a global difference.
C
It is a claim that the argument is directed against.
The referenced text supports the argument. Why would iron-fortified salt reduce anemia in the world’s population? Because people around the world use enough salt that the iron fortification would have an effect.
D
It qualifies the conclusion of the argument.
The conclusion is that iron-fortified salt would reduce the general incidence of anemia. The referenced text supports that claim rather than qualifying its scope.
E
It illustrates a principle that underlies the argument.
The referenced text isn’t a principle. It’s a fact used to support the conclusion about iron-fortified salt reducing anemia.
Summarize Argument
The author concludes that people are wrong to say that we should learn the lessons of history. This is because the lessons are difficult to discern, and it’s not certain they could ever be applied even if we discovered them.
Identify Argument Part
The referenced text is the position that the author’s argument is disputing. Even trying to learn the lessons of history, the author argues, is ultimately a waste of time.
A
It sets out a problem the argument as a whole is designed to resolve.
The argument isn’t trying to resolve a problem. It’s disputing the view—that we should learn the lessons of history—expressed in the referenced text.
B
It is compatible with accepting the argument’s conclusion and with denying it.
The author concludes that discovering the lessons of history is a fruitless task. The referenced text meanwhile states that we should try to discover them, which contradicts the conclusion.
C
It is a position that the argument simply takes for granted is false.
The author doesn’t take for granted that we shouldn’t learn the lessons of history. Instead, she argues it’s a pointless endeavor to undertake.
D
It expresses the position the argument as a whole is directed toward discrediting.
The referenced text says that we should learn the lessons of history. The author says we shouldn’t, since the lessons of history are difficult to discover and of little practical value. Thus, the author attempts to discredit the position expressed in the referenced text.
E
It is an assumption that is required in order to establish the argument’s conclusion.
The author doesn’t assume that we should learn the lessons of history. Instead, she argues against this position.
Summarize Argument
The author concludes that social inertia plays a greater role in human behavior than the desire for comfort or safety. As evidence, he cites the fact that many historical innovations were resisted by people whose lives these innovations would’ve improved.
Notable Assumptions
The author assumes that resisting technological innovation constitutes social inertia. He also assumes that people didn’t resist technological innovation for some reason other than social inertia. Finally, the author assumes that “many examples” of this one phenomenon are enough to draw a claim about the relative power of forces determining human behavior.
A
People correctly believe that technological innovations often cause job loss.
Social inertia wasn’t the reason why people resisted technological innovation. They were rightly concerned about losing their jobs.
B
People are often reluctant to take on new challenges.
That “reluctance” sounds like social inertia. Besides, we have no evidence these technological innovations were “challenges.”
C
Some examples of technological innovation have been embraced by workers.
This points out an exception. The author, however, doesn’t need his very general conclusion to be true in all historical cases. Social inertia may still be more powerful than the desire for comfort—just not always.
D
People tend to adapt easily to gradually implemented technological innovations.
If this is true, then in many cases technological innovations haven’t been implemented gradually. People evidently didn’t adapt easily in those cases, hence the resistance.
E
People correctly believe that technological innovations almost always increase workers’ productivity.
If this is true, why are workers resisting? Inertia would seem to be a totally valid hypothesis. We need something that weakens that hypothesis.