Macrophages can act as antigen presenting cells after phagocytosing a pathogen such as a bacterium After digesting the bacterium in the lysosome, a portion of the bacterium is presented on surface in association with the macrophage molecule ______ This bacterially derived molecule interacts with a receptor on the surface of the T helper cell to help initiate a specific immune response

a. Fc receptor
b. Interleukin 2 receptor
c. Major Histocompatibility Complex (MHC) class II
d. leukotriene receptor