While B Cells and T Cells Differ Markedly in Their

While B cells and T cells differ markedly in their functions during an immune response, the two lymphocyte subsets share the enzymatic machinery and overall scheme for generating antigen receptor diversity. This is because:

A) B cells and T cells recognize the same form of antigen expressed by an infecting pathogen.
B) Animals with B cells developed first, and later evolving species then developed T cells.
C) B cells and T cells both need enormous antigen receptor diversity to provide protection against the diversity of pathogens.
D) Antibody and T-cell receptor gene segments are both flanked by similar recombination signal sequences.
E) B cells and T cells both secrete their antigen receptor proteins after they are activated by antigen-binding.