Charles,who is 55 years old,did not realize how much his physical appearance had changed until he saw a picture of himself taken 20 years ago.Charles's gradual change in physical appearance was due to:

A) senescence.
B) homeostasis.
C) organ reserve.
D) allostasis.

Senescence

The process of aging where the biological functions of an organism decline, leading to decreased ability to adapt to stress and increased risk of death.

Physical Appearance

The outward look or aspect of a person, including features, shape, and style of dress, which can influence social perceptions.