Fact 1: Aging is associated with the death of cells. Fact 2: Apoptosis means cell death. Given the two facts above, what is a natural part of aging?

(a). Smoking; (b). apoptosis; (c). regeneration; (d). illness; (e). stimulation; (f). cracking; (g). Weight; (h). firm skin;
The answer is:
(b).