Correct Option: B

Affinity maturation is the process by which THC cell-activated B cells produce antibodies with increased affinity for antigen during the course of an immune response. With repeated exposures to the same antigen, a host will produce antibodies of successively greater affinities once the memory has been generated.  Whereas Isotope switching refers to the generation of IgA, IgD, IgM, IgE, IgG from IgM in response to a particular Ag. For e.g.: IgM will undergo isotope switching to IgE in response to Allergen reaction.