Aging is the process of growing old. It occurs eventually in every living thing provided, of course, that an illness or accident does not kill it prematurely
What is the main idea in the first paragraph?
A. Signs of aging are easier to detect in animals than in plants.
B. The outward signs of aging may be seen in old people.
C. Aging occurs in every living thing after it has reached maturity.
D. Not all signs of aging are visible.