Answer:
B and T cells.
Explanation:
B cells and T cells are cells of adaptive immune system, which shows specificity, memory, and diversity against pathogens. When a particular antigen enters to the body, it triggers immune responses that activate naive B cells and T cells.
During activation, these cells divide to form 'effector B and T cells' that provide immediate responses against that antigen, and 'memory B and T cells' that provide response against that particular antigen during next or subsequent infections.
Thus, the correct answer is option). B and T cells.
