Final answer:
A. Affinity maturation. Affinity maturation is the process that involves the mutation of immune receptors during an immune response to generate higher-affinity receptors.
Step-by-step explanation:
The process that involves the mutation of immune receptors during an immune response to generate higher-affinity receptors is Affinity maturation. Affinity maturation occurs in the context of B cell maturation, specifically in the production of antibodies by B cells.
During affinity maturation, B cells undergo mutations in their immunoglobulin gene variable regions, resulting in B cells with slightly altered antigen-binding sites. On re-exposure to the antigen, those B cells capable of producing antibody with higher affinity antigen-binding sites will be stimulated to proliferate and produce more antibody than their lower-affinity peers.