Q.Paratope is an (A) Antibody binding site on variable regions (B) Antibody binding site on heavy regions (C) Antigen binding site on variable regions (D) Antigen binding site on heavy regions

Antigen-antibody binding is the molecular basis of humoral immunity and proceeds in three stages: complex formation, a visible reaction (precipitation or agglutination), and finally destruction or neutralisation of the antigen. Binding strength (antibody affinity) depends on how closely antigen and antibody fit, the sum of non-covalent forces holding them (hydrogen bonds, electrostatic forces, Van der Waals forces, hydrophobic interactions), and the antibody's intrinsic affinity. The physical form of the antigen determines the visible outcome: soluble antigens produce precipitation (via precipitins), particulate antigens produce agglutination (via agglutinins). Opsonisation is a related process in which antibody coating a pathogen (as an opsonin) makes it far more efficiently engulfed by phagocytes, and neutralisation reactions use specific antibodies (antitoxins) to cancel the harmful effects of bacterial exotoxins or viruses.