Q: Fact 1: Cancer is a disease that occurs when the cell cycle is no longer regulated. Fact 2: Another critical protein in regulating the cell cycle is the tumor suppressor protein p53 . Given the two facts above, one tumor suppressor protein which often results in cancer when it stops functioning is:?

Available choices:
a). gene;
b). p53;
c). tumors;
d). HIV;
e). enzyme;
f). tRNA;
g). DNA;
h). TRH;
A:
b).