One important factor that affects the correctness of the results is that_________.A. the o

One important factor that affects the correctness of the results 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

答 案：A
A[解析]由第四段的“Those results could be improper because the studies in-volved older people，and women Iive longer than men.”可以推出A项正确。