Lymphocytes include which cells?

• A. Red blood cells
• B. Platelets
• C. Natural killer cells, B cells, and T cells
• D. Neutrophils

Answer: (C)

Lymphocytes are a type of white blood cell that drive immune responses, including both adaptive and certain innate-like activities. They include natural killer cells, B cells, and T cells. Red blood cells and platelets are not white blood cells—they handle oxygen transport and clotting, respectively. Neutrophils are also white blood cells, but they are granulocytes involved mainly in the immediate innate response, not lymphocytes. So the group that contains natural killer cells, B cells, and T cells are all lymphocytes, making that the correct choice.