Immunoglobulin Diversity and T Cell Receptor Diversity Both Involve Random

Immunoglobulin diversity and T cell receptor diversity both involve random recombinational events to create diversity

A) After antigen exposure, B and T cells also have somatic mutational events to improve affinity.
B) After antigen exposure, B cells have somatic mutational events to improve affinity, but T cells do not.
C) Before antigen exposure, B cells have somatic mutational events to improve affinity, but T cells do not.
D) Before antigen exposure, B and T cells have somatic mutational events to improve affinity.