单选题 The doctor's tests show that ______.

A、 our brains shrink as we grow older
B、 the front section of the brain does not shrink
C、 sixty-year-olds have better brains than thirty-year-olds
D、 some people’s brains have contracted more than other people’s

【正确答案】 D

【答案解析】[解析] “the findings show in general terms that contraction of the brains sooner in people in the country than in the town”“一些人的大脑比另外一些人的萎缩得要快，所以选择答案D。