What is the type of physiological change that takes place during adulthood around the age of 30?

A. The lens of the eye start to stiffen and thicken

B. Skin becomes drier and wrinkle starts to appear

C. Age spots and blood vessels become more apparent as the skin continues to dry and get thinner

D. The immune system becomes less adapt at fighting of illness and reproductive capacity starts to decline

Answer: Option A