Antigen antibody precipitation is maximally seenin which of the following?

Equivalence of antibody and antigen Precipitation reaction It is a type of antigen antibody reaction - When a soluble antigen combines with its antibody in the presence of electrolytes (NaCI) at a suitable temperature and pH, the antigen antibody complex forms an isoluble precipitate. . The amount of precipitate formed is greatly influenced by the relative propoions of antigens and antibodies. - Precipitation occurs most rapidly and abundantly in the zone of equivalence in which the antigen and antibody are present in optimal propoions. . If increasing quantities of antigens are added to the same amount of antiserum in different tubes and the amounts of precipitate in different tubes are plotted on a graph, the resulting curve will have three phases: