Which of the following methods is used in the analysis of item discriminability?

According to our discussion of the article Over the Hill about the Betula study of adult cognition, long term longitudinal studies are:

(a) probably seriously flawed by the unrepresentativeness of the later samples (b) the best method yet devised for studying psychology over the lifespan (c) the only way to overcome cohort effects as confounds (d) so difficult to do that only one has been completed

In aging males, a drop in testosterone levels may be connected to

A) reduced testicular size. B) a rise in bone mass. C) a reduction in body fat. D) a reduction in muscle mass.