In order for B cells to produce antibodies and cytotoxic T cells to attack infected host cells, they must first:
a. recognize self markers, develop specificity for the markers, and then produce clones.
b. encounter an antigen, develop specificity for that antigen, and then remember the antigen.
c. be activated by interleukins, encounter an antigen, and then develop specificity toward it.
d. undergo maturation, encounter their specific antigen target, and then become activated through cytokines.