What factors may contribute to aging?
ca celis stop dividing after 50 divisions
b. cells become more and more damaged.
c genes tell" cells to stop dividing.
d. all of the above

The factor that contributes to aging is: A Cells stop dividing after 50 divisions.

Explanation:

Normally after 40 to 50 divisions the cells stops dividing because they had already lost too much DNA for other divisions. So they eventually die, making the appearance like an aged person in any individual. As DNA is copied in every cell division process, they tend to loose small part of telomeres in each transfer process. Hence, after 50 divisions these cells fails to divide resulting in aging.