Everyone becomes a little more forgetful a
问题：
Everyone becomes a little more forgetful as they get older, but men’s minds decline more than women’s, according to the results of a worldwide survey.
Certain differences seem to be inherent in male and female brains: Men are better at maintaining and dealing with mental images (useful in mathematical reasoning and spatial skills), while women tend to excel (擅长) at recalling information from their brain’s files ( helpful with language skills and remembering the locations of objects).
Many studies have looked for a connection between sex and the amount of mental decline (衰退) people experience as they age, but the results have been mixed.
Some studies found more age-related decline in men than in women, while others saw the opposite or even no relationship at all between sex and mental decline. Those results could be improper because the studies involved older people, and women live longer than men: The men tested are the survivors, "so they’re the ones that may not have shown such cognitive decline," said study team leader Elizabeth of the University of Warwick in England.
People surveyed completed four tasks that tested sex-related cognitive skills : matching an object to its rotated form, matching lines shown from the same angle, typing as many words in a particular category (范畴) as possible in the given time, e.g. "object usually colored gray", and recalling the location of objects in a line drawing. The first two were tasks at which men usually excel; the latter were typically dominated by women.
Within each age group studied, men and women performed better in their separate categories on average. And though performance declined with age for both genders, women showed obviously less decline than men overall.
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