单选题 The doctor's test show that ______.

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

【正确答案】 D

【答案解析】[精解] 是非判断题，根据倒数第二段第一句的内容可以得知。