OG5 阅读 Q49

Choice C is the best answer. The passage indicates that Maguire's second study revealed that people in the control group don't have different brain structures than the mental athletes but that they use their brains differently. In particular, the two groups use different pathways in the brain: "regions of the brain that were less active in the control subjects seemed to be working in overdrive for the mental athletes" (lines 63-65,"functional...athletes"). 
Choices A and D are incorrect because the passage states that there was only "one telling difference between the brains of the mental athletes and the control subjects" (lines 57-58,"But...subjects"); there is no indication that the control group showed less total brain activity or had smaller hippocampal regions. Choice B is incorrect because the passage mentions only the general cognitive ability of the mental athletes, noting that their scores were "within the normal range" (line 54,"scores ...The").