PrepTest 151, Section 4, Question 21
Evolution does not always optimize survival of an(74 more words not shown)
Which one of the following(9 more words not shown)
- Aciting an example(7 more words not shown)
- Bemploying an analogy(6 more words not shown)
- Cchallenging a general(5 more words not shown)
- Ddisputing the relevance(9 more words not shown)
- Eundermining a claim(6 more words not shown)
Reading the argument
Aren't the large antlers helping the moose reproduce?
That is my first reaction to calling them a disadvantage. The antlers help males compete for mates, even though they can catch in trees when the moose tries to escape predators. A benefit in one respect can come with a cost in another. But notice the opening claim: it concerns optimizing survival, not whether the antlers offer any benefit at all.
The last sentence also matters. The author isn't proposing that just one male shrink its antlers and lose its advantage over rivals. All the males would have antlers half as large. The biggest would still be the biggest relative to the others, while everyone would be less vulnerable to predators.
What we’re looking for
We're being asked how the author reasons. My initial description would be that the moose example supports the opening claim. Keep that role in mind as we compare the answers' more specific descriptions.
Working the answers
- A
The passage certainly uses an example, which makes this tempting. But where is the competing argument? We aren't given someone else's premises and conclusion to challenge. The author uses the moose to challenge a general idea about what evolution always does. C describes that more precisely. A counterexample is still an example; the problem with A is its description of the target, not that word.
- B
An analogy would compare the moose case with a different case and use their similarity to make a point. Here the moose is itself a case of evolution being assessed under the general claim. The author doesn't reason from one comparable situation to another.
- CCorrect
'Evolution does not always optimize survival' challenges the general claim that it always does. The moose is offered as a case in which evolved antlers leave a survival disadvantage that the proposed smaller antlers would avoid. One counterexample is enough to challenge an 'always' claim.
We don't need outside knowledge about what biologists believe to identify that general claim. It is the claim denied by the opening sentence. The example both supports the author's 'not always' conclusion and works against the corresponding 'always' claim.
- D
We might question how well the example works while reading, but the author isn't disputing its relevance. The author presents the moose as relevant support for the opening claim. Don't substitute a reader's possible objection for the technique the argument itself uses.
- E
A trait helping reproduction while hindering escape isn't a self-contradiction. Those are different effects. The author offers a case meant to show that survival isn't always optimized, rather than showing that a claim asserts and denies the same thing.
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