Final answer:
The major contribution of B cells to the immune response is to produce antibodies. B cells are a critical component of the humoral immunity and function to recognize pathogens and their antigens.
So, the correct answer is D. Produce antibodies.
Step-by-step explanation:
B cells mainly contribute to the immune response by producing antibodies, which bind to antigens on pathogens, targeting them for destruction. Once a B cell encounters its specific antigen, it can proliferate and differentiate into plasma cells, which secrete antibodies. These antibodies bind specifically to antigens found on pathogens, such as bacteria and viruses, marking them for destruction by other immune cells like phagocytes. The production of antibodies by B cells is essential for protecting the body against extracellular pathogens and toxins.
On the other hand, other immune cells like T cells and natural killer cells play different roles. T cells may help B cells in the immune response by secreting cytokines, assisting in their proliferation and maturity into plasma cells. Natural killer cells, for instance, secrete cytokines such as interferons to support the immune response but are more directly involved in killing infected or abnormal cells.
So, the correct answer is D. Produce antibodies.