Correct Option: B

T cell recognition of antigen requires that a complex form between peptides derived from the protein antigen and cell surface glycoproteins encoded by genes within the major histocompatibilty complex (MHC). MHC class II molecules present both extracellular (exogenous) and internally synthesized (endogenous) antigens to the CD4 T cells subset of lymphocytes. Endogenous antigens are internally generated molecules that become presented on the cell surface in the complex with class I histocompatibilty molecules (MHC I). Endogenous antigens may result from exogenous viral or bacterial infections that have altered the host cell. In autoimmune disorders, endogenous, self-molecules induce autoimmune attack by CD8+ Tc/CTLs that have escaped negative selection in the thymus.