Explanation:

The overall ability of the body to fight the diseasecausing organisms (pathogens), conferred by the immune system is called immunity. The primary and secondary immune responses are carried out with the help of two special types of lymphocytes present in our blood, i.e., B-lymphocytes (B-cells) and T-lymphocytes (T-cells). Thus, both B-cells and T-cells are responsible for acquired immunity. B-cells are responsible for antibody-mediated immunity response. T-cells are responsible for cell-mediated immunity response. Bcells produce antibodies to fight with the pathogens into our blood. The T-cells themselves do not secrete antibodies but help B cells produce them. Hence option (d) is the correct answer.