Answer:
Psychological.
Step-by-step explanation:
Aging may be defined as the biological process of getting old day by day. The aging might occur due to the formation of the reactive oxygen species and the shortening of the telomeres.
The psychological theory of aging include the three different theories - disengagement theory, continuity theory and activity theory. These theories mainly focus on the psychological resources that affects the human health and diminishes the efficacy with the increasing age.
Thus, the answer is psychological.