Cranial Size

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A theory argues that racial differences can lead to differences in cranial size and, in turn, brain size. However, another study suggests that humans who grow up farther from the equator are exposed to less ambient sunlight and therefore develop larger eyes, which in turn lead to larger visual cortices, increasing total brain size. Since the populations of some races are concentrated closer to the equator and the populations of other races are concentrated farther from the equator, data that appear to support the racial theory of brain size may fit the ambient-light theory of brain size equally well or even better.

In the argument given, the two portions in boldface play which of the following roles?

The ﬁrst is an objection that has been raised against a position defended in the argument; the second is that position.

The ﬁrst is evidence that has been used to support an explanation that the argument challenges; the second is that explanation.

The ﬁrst is evidence that has been used to support an explanation that the argument challenges; the second is a competing explanation that the argument favors.

The ﬁrst is a claim, the accuracy of which is at issue in the argument; the second is an objection to that claim.

The ﬁrst is a claim, the accuracy of which is at issue in the argument; the second is a conclusion about the likelihood of accuracy of that claim.

Review: Cranial Size

Explanation

Reading the question: since we have boldfaced text, we don't need to analyze the argument. We will just identify the logical role of each sentence.

Sentence

Starts With.../Includes...

Function

1st

"A theory argues"

States a theory

2nd

"However, another study suggests that humans"

States another theory

3rd

"Since the populations"

Fact

3rd

"data that appear to support the racial theory"

Opinion about theories

Sentence 1 states a theory, and sentence 2 states another theory; the bold part is the content of the belief of the second theory. Then we have some un-bolded evidence, and then the conclusion, in bold, the first hint of the author's opinion, which is a comparison of the theories.

Applying the filter: Let's see which answer choices get the first statement right. The first statement isn't an objection or evidence. That leaves only (D) and (E). The author's position is that evidence for the racial theory could be construed as support for the ambient-light theory. The author favors the ambient-light theory, which is expressed in the first statement. So the two bolded statements are in harmony. That rules out (D), and also confirms that (B) and (C) are out. And the first statement definitely isn't an objection, so (A) is out. The correct answer is (E).

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Cranial Size