Place the Events of Clonal Selection and Expansion in the Correct

Place the events of clonal selection and expansion in the correct order.
1) Differentiation of cells into a formidable army of effector cells.
2) The binding of an antigen to a preprogrammed receptor selects the lymphocyte that undergoes rapid cell division.
3) Cytokine secretion leads to activation of pathogen-eliminating mechanisms.
4) Memory cells disseminate throughout the body and wait to eliminate future invading pathogens.

A) 1, 2, 3, 4
B) 4, 3, 2, 1
C) 2, 1, 4, 3
D) 2, 4, 3, 1