Answer: Option II.
B cells and T cells undergo colonial selection after encountering an antigen.
Step-by-step explanation:
B cells are a type of lymphocytes or white blood cells that produce hormones so as to activate the immune system in other to provide a defence or fight against pathogens.
T cells are lymphocytes immune cells that fight against pathogens in the body.
Both T cells and B cells undergo colonial selection after encountering an antigen. The major difference between them is that T cells