There are a variety of lymphocytes involved in the adaptive response, each with a specific function. One of the subsets of cells essential in the adaptive response is T helper cells. Choose the answer that most accurately describes the role of T helper cells in mounting the antibody response.

a. T helper cells present antigens to B cells, which is required for their activation.
b. T helper cells aid in the response by killing infected cells while the antibody response mounts.
c. T helper cells aid the antibody response by binding to the B cell MHCII/protein complex and secreting cytokines like IL-4.
d. T helper cells secrete IL-2, which is required for clonal expansion of B cells.