Final answer:
Immunologic tolerance is a result of negative selection of T cells in the thymus, clonal anergy in the peripheral lymphoid organs, and positive selection of T cells in the thymus.
Step-by-step explanation:
Immunologic tolerance is a result of negative selection of T cells capable of recognizing self-peptides in the thymus, clonal anergy of T cells capable of recognizing self-peptides in the peripheral lymphoid organs, and positive selection of T cells capable of recognizing self-MHC in the thymus. These processes of thymic selection ensure the maturation of T cells that are able to recognize foreign antigens presented by MHC molecules, while preventing the activation of T cells that could cause autoimmunity by recognizing self-antigens.