PrepTest 119, Section 3, Question 18
A seriously maladaptive trait is unlikely to persist(54 more words not shown)
The proposition that those lacking(22 more words not shown)
- AIt expresses a(11 more words not shown)
- BIt is the(3 more words not shown)
- CIt is a(4 more words not shown)
- DIt presents evidence(6 more words not shown)
- EIt is an(5 more words not shown)
Reading the argument
If a trait puts an animal at a serious disadvantage, I can see why that trait might fade from the population. The passage gives us an explanation: some animals lack the trait, those animals compete more successfully, and that advantage lets them survive and reproduce more often. Over time, they crowd out the animals that have the trait.
Now separate the steps. The main point is the opening claim that the seriously disadvantageous trait is unlikely to persist for long. The facts about variation, competition, survival, and reproduction explain why. The question singles out the statement that animals without the trait compete more successfully. The author takes that statement as a starting reason, then uses it to support the claim about their higher survival and reproduction. We aren't given a separate argument establishing their competitive advantage.
What we’re looking for
That makes the selected statement a premise. Don't decide its role by its position, or by spotting hence later on. Follow what supports what: this competitive advantage helps explain the survival advantage, which helps explain why the trait disappears.
Working the answers
- A
The author relies on the competitive advantage rather than trying to discredit it. If the animals without the trait didn't compete more successfully, this explanation for their eventual dominance would lose an important step. A points in the opposite direction from the statement's role.
- B
The main conclusion concerns how long the maladaptive trait will persist in the population. The selected claim about competition helps support that conclusion. It answers part of why the trait is unlikely to persist; it isn't the overall point being explained.
- CCorrect
The claim is used as a reason to believe the animals lacking the trait will survive and reproduce at higher rates. That, in turn, supports the eventual crowding-out claim and the main conclusion about the trait's disappearance. The competitive-advantage claim supplies support without receiving separate support here.
- D
The statement does supply evidence, but the argument doesn't undermine it. It builds on it. The second half of D reverses the author's treatment of this claim, so the partly accurate first half cannot make the whole answer right.
- E
An intermediate conclusion both receives support and supports something else. The selected statement does the second job, but the passage doesn't offer separate reasons for believing it. The later claim about higher survival and reproduction is supported by the competitive advantage; that isn't the statement the question asks us to classify.
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