Final answer:
People who are deficient in CD 4 T cells are more susceptible to cancer because these cells play a crucial role in regulating the immune response and activating other immune cells.
Step-by-step explanation:
People who are deficient in CD 4 T cells are more susceptible to cancer. CD4 T cells, also known as helper T cells, play a crucial role in regulating the immune response. They help activate other immune cells, including cytotoxic T cells and B cells, which are responsible for destroying cancer cells. Without sufficient CD4 T cells, the body's immune system is compromised, making it easier for cancer cells to proliferate and evade immune surveillance.