Indicate the true statements and correct the false statements so they are true.
a. B cells are activated by antigen-presenting cells.
b. T cytotoxic cells are activated by antigens bound to MHC I.
c. Upon activation, T helper cells stimulate T cytotoxic cells and B cells.
d. IgG is the first antibody made during a primary response.
e. T-dependent antigens rely on TH cells to activate B cells.