How Does the Phrase "Use It or Lose It" Apply

How does the phrase "use it or lose it" apply to the relationship between aging and sexuality?

A) Aging individuals envy younger people and their greater sexual responsiveness.
B) Little sexual responsiveness and interest are lost over the lifespan.
C) The loss of sexual responsiveness over the years often results in inappropriate or even dangerous sexual behavior among the aging.
D) Those who remain sexually active appear to retain their sexual capacity and responsiveness.