The portion of the antigen molecule which is recognized by antibody is known as:

Ans. B. EpitopeEpitope is a localized region on the surface of an antigen that is capable of eliciting an immune response and of combining with a specific antibody to counter that response. Hapten is a small molecule that reacts with a specific antibody but cannot induce the formation of antibodies unless bound to a carrier protein or other large antigenic molecule. A complement is a complex system of proteins found in normal blood plasma that combines with antibodies to destroy pathogenic bacteria and other foreign cells. Also called alexin. A variable region is present in the antibody that shows many sequence differences between antibodies of different specificities; the part of the antibody that binds to the antigen.