PrepTest 124, Section 1, Question 20
Biologist: Lions and tigers are so similar to(52 more words not shown)
The conclusion is properly drawn(8 more words not shown)
- AThe skeletons of(24 more words not shown)
- BThere have existed(22 more words not shown)
- CIf skeletal anatomy(33 more words not shown)
- DIf any two(37 more words not shown)
- EIf it is(35 more words not shown)
Reading the argument
A lion and a tiger can have almost indistinguishable skeletons and still hunt differently. That makes me cautious about reading hunting behavior straight from bones. But does it settle what every other animal's skeleton could tell us?
Perhaps a dinosaur had a particular skeletal feature that reliably indicated pack hunting. The lion-and-tiger example wouldn't rule out such a feature just because those cats don't give us a useful skeletal distinction. We need a reason the failure in this example applies to the extinct animals too.
The question asks for an assumption that makes the conclusion follow. Our target is specific: it isn't reasonable to infer pack hunting from skeletal anatomy alone. We don't need to prove the dinosaurs hunted alone or deny that other kinds of evidence could reveal their behavior.
What we’re looking for
I'd look for a rule carrying the limitation we see in lions and tigers over to the broader claim about other species. If one example of inadequate skeletal evidence rules out this kind of inference generally, the conclusion would follow.
Working the answers
- A
Similarity in some respects isn't enough. Lions and dinosaurs might share certain skeletal features while differing in another feature relevant to hunting. A leaves our objection open: perhaps the dinosaur's other features reveal something the cats' skeletons don't. We need the broader limitation established, not just some resemblance.
- B
Two dinosaurs having similar skeletons doesn't tell us whether their hunting behavior differed. They might both have hunted in packs. Even another pair with matching bones wouldn't by itself establish that skeletal anatomy can never justify the inference the author rejects.
- CCorrect
This gives the broad rule we need. The lion-and-tiger case shows skeletal anatomy alone can be inadequate for determining hunting behavior: virtually indistinguishable skeletons go with different behavior. C says that if anatomy alone is ever inadequate, it is never reasonable to infer pack hunting from anatomy alone.
That rule reaches the dinosaurs as well as the modern animals. It's a very strong assumption, but this question allows a strong rule that makes the conclusion follow. We are not being asked to show that such a sweeping rule is scientifically true.
- D
The opening condition fits the lions and tigers, but the resulting rule concerns inferring skeletal anatomy from hunting behavior. Our conclusion goes from skeletal anatomy to hunting behavior. Knowing what we can't infer about bones from behavior doesn't establish what we can't infer about behavior from bones.
- E
This conditional ends by saying two species' skeletal remains are virtually indistinguishable. That isn't the conclusion we need. We need a rule barring a pack-hunting inference based only on bones, not a rule telling us when two sets of remains must look alike. E doesn't connect the lion-and-tiger evidence to that broader restriction.
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