The correct option is D MHC antigen complex
T-lymphocytes are involved in both humoral and cell mediated immunity. T-cells largely recognize proteins that have been processed within antigen presenting cells and are presented on the cell surface bound to a molecule known as Major Histocompatibility Complex (MHC). the T-cells cannot recognize free antigen and can only recognize and interact with the MHC antigen complex. Thus, the correct option is D.