All your cells contain proto-oncogenes, which can change into cancer-causing genes. why do cells possess such potential time bombs?
a. cells produce proto-oncogenes as a by-product of mitosis.
b. proto-oncogenes are necessary for the normal control of cell growth and division.
c. proto-oncogenes protect cells from infection by cancer-causing viruses.
d. proto-oncogenes are unavoidable environmental carcinogens.
e. proto-oncogenes are genetic junk that has not yet been eliminated by natural selection.

B

Explanation:

Proto-oncogenes contain proteins that stimulate cell division, inhibit cell differentiation,and prevent cells from dying. These processes are important for normal development and for the maintenance of tissues and organs.

An alternation of these proto-oncogenes leads to the formation of oncogenes which are particularly responsible for abnormal cell division resulting in cancer cells

the correct choice is a .

do not post any more test or exam questions on

one person pulls 90n one way and the other has 100n pulling the other way.

so the net force = 90 - 100 = -10n,

or the ans can be 10n if the picture shows -90n and 100n instead.