Cranial Size Welcome! You are encouraged to register with the site and login (for free). When you register, you support the site and your question history is saved.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 Answer