Affinity Is Described as Which of the Following

Affinity is described as which of the following?

A) The overall strength of binding of an antibody to an antigen and includes the sum of the binding affinities of all the individual binding sites on the antibody
B) Another substance that is capable of producing antibodies
C) The thermodynamic quantity defining the energy of interaction of a single antibody-binding site and its corresponding epitope on the antigen
D) A chemical substance capable of inducing an immune response