PrepTest 113, Section 4, Question 18
A plausible explanation of the disappearance of the(39 more words not shown)
Which one of the following(8 more words not shown)
- AOne of the(22 more words not shown)
- BVarious species of(24 more words not shown)
- CIt cannot be(18 more words not shown)
- DMany other animal(18 more words not shown)
- EThe consequences for(13 more words not shown)
Reading the argument
I can follow that explanation: a collision throws up dust, the dust affects the climate, and the change becomes fatal to dinosaurs. But describing a possible sequence doesn't establish that it happened.
What we’re looking for
If we're going to weaken the comet theory, my first thoughts are to question the collision or its proposed effects. Perhaps there is evidence against an impact at the relevant time, or perhaps such an impact wouldn't cause the sustained cooling the explanation needs. Those are possible directions to look, not facts we've been given. We only need evidence that makes the explanation less plausible; we don't have to rule it out completely.
Working the answers
- A
Another school of thought favors a different explanation. What evidence supports it? Without the reasons for that view, we can't evaluate whether it exposes a problem with the comet theory. The existence of disagreement is much less informative than a fact that the proposed explanation has trouble accounting for.
- BCorrect
Why did comparable animals survive? These species lived at the same time as the dinosaurs and had similar bodies and habitats. If the proposed environmental change was severe enough to wipe out the dinosaurs, the survival of animals with those similarities calls for an explanation.
This is a different approach from my initial guesses about whether a collision occurred or caused cooling. B challenges the fit between the proposed cause and the extinction pattern. Similar species needn't react identically, so B doesn't prove the comet theory false. But the similarities make their survival harder to brush aside. That's what gives B its force.
- C
An inconclusive test isn't a contrary result. If skeletons can't tell us whether the animals died from the dust cloud's effects, they haven't shown that those effects weren't responsible. Cooling would be one of the proposed effects. This method's inability to identify the cause leaves that explanation open; it doesn't give us evidence against it.
- D
This is close to B, but it leaves out the important comparison. Other species might have very different bodies or live in environments that protected them from the changes. For example, we could investigate whether an aquatic habitat offered some protection; that is a possibility, not a claim about what actually happened. The mere survival of other animals doesn't challenge the theory as directly as the survival of animals similar to the dinosaurs in both physiology and habitat.
- E
We don't need to understand every consequence to have a plausible explanation of one consequence. You could know that a large impact would damage a building without predicting every piece of damage. Likewise, an incomplete understanding of a comet's effects could still include good evidence for the particular cooling effect described here. E doesn't identify a problem with that proposed sequence.
More Weaken questions
Learn the LSAT our way
Our platform drills Weaken questions at your level and adjusts as you improve.