Tumor-suppressor genes:
A. are frequently overexpressed in cancerous cells.
B. are cancer-causing genes introduced into cells by viruses.
C. can encode proteins that promote DNA repair or cell-cell adhesion.
D. often encode proteins that stimulate the cell cycle.
E. do all of these.

Option C.

Explanation:

Tumor suppressor genes are genes that help to control cell growth or division. It cause the production of protein which is important in cell growth. It encode protein that slow or inhibit progression in a specific stage of cell cycle leading to DNA repair or cell adhession. If the cells grow uncontrollable, it leads to cancer. When there is mutation of tumor suppressor genes,it result in reduction in its function.

i think the answer is

mass