Patricia and Jon have observed that they are having less sex than they did back in their thirties. This is MOST likely due to

A) physiological changes exclusively.
B) the tendency to find extramarital sex more exciting.
C) fatigue from work and childrearing.
D) a decrease in the ability to have orgasms.

Fatigue from work and childrearing is a common reason for a decrease in sexual activity among middle-aged couples. Physiological changes may also play a role, but they are unlikely to be the only contributing factor. There is no evidence to suggest that finding extramarital sex more exciting or a decrease in ability to have orgasms are the primary reasons for the decrease in sexual activity.