The correct answer is option B. "proto-oncogenes".
Explanation:
Tumor suppressor genes and proto-oncogenes are two types of genes that can cause the development of cancer cells if they suffer a mutation. The main difference between tumor suppressor genes and proto-oncogenes is the way they cause cancer. If tumor suppressor genes are inactivated they produce cancer cells, while if proto-oncogenes are activated is when they produce cancer cells.
