(单选题)

One important factor that affects the correctness of the result is that ______.

A.the old men tested may not have shown such cognitive decline

B.people surveyed are all old

C.people taking part in this test came from all over the world

D.women live longer than men

参考答案：A

参考解析：

细节理解题。根据第四段第二句“Those results could be improper because the studies involved older people. The men tested are the survivors, ‘so they’re the ones that may not have shown such cognitive decline,’”可知，这些结果可能是不恰当的，因为这些研究涉及老年人，而这些受试的老年人是幸存者，所以他们可能没有表现出认知能力的下降。故A项正确。文章只是说调查涉及到老年人，但并不都是老年人，故排除B。C选项文中未提及。选项D不是造成调查结果不准确的原因。故选A。

知识点：阅读理解四选一英语专业基础知识阅读理解教师招聘-小学英语