Nancy Denney Uses the Concepts of "Exercised" and "Unexercised" Skills

Nancy Denney uses the concepts of "exercised" and "unexercised" skills to propose a model of physical and cognitive change in adulthood.Which of the following is most consistent with Denney's view of age-related change in physical and cognitive functioning?

A) If a skill is unexercised for any length of time, or becomes "rusty," exercise will not cause any improvement.
B) There is an underlying decay curve, so that with increased age there will eventually be a point at which even maximum exercise will not help an individual maintain peak functioning in either physical or cognitive abilities.
C) Early adulthood is the time of peak function in physical and cognitive abilities, and even young adults who are not exercising their skills will be able to outperform middle-aged adults who are exercising their physical and cognitive abilities.
D) Physical exercise will facilitate maintenance of physical abilities through adulthood, but no equivalent improvement can be made in cognitive functioning.