The basis for the control which MHC molecules have over the immune response is best explained by the:

A. ability of MHC-antigen complexes to be released from antigen presenting cells and stimulate the activation of lymphocytes.

B. expression of MHC gene products on effector T and B lymphocytes

C. existence of genes controlling the immune response in linkage disequilibrium with MHC genes.

D. need for antigen-derived peptides to bind an MHC class I or class II molecule for proper presentation to the receptor of a T lymphocyte.

E. special affinity of unprocessed antigens for MHC molecules.