All of the Following Are Important Aspects of Competitive-Binding Assays

All of the following are important aspects of competitive-binding assays except:

A) There must be non-covalent and reversible binding of the antigen to the antibody.
B) The antigenic determinant of the labeled antigen must not be altered by the addition of the label.
C) There must be a limited number of binding sites on the antibody used in the assay.
D) The antigen being measured must be large enough to provoke an immune response.