This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
Which of the follwoing molecular phenomenon in Ig genes is responsible for affinity maturation of antibody response 
Select and explain. 
A. Chain shuffling, B. Junctional diverity, C. Somatic hypermutation, D. Altered RAA splicing
C: Somatic hypermutation
Answer: C: Somatic hypermutation 
Explanation: C i.e. Somatic Hypermutation Affinity Maturation refers to the increased affinity of antibodies for their specific antigen as the antibody response continues. This phenomenon is not seen in IgM responses. Those B-cells expressing receptors with a higher affinity for the antigen are selctively expanded, even as the levels of antigen fall. Thus B-cells with higher affinity are generated during the 1deg & 2deg immune respones in large pa due to Somatic hypermutations that occur in VI I genesQ. (VH =Variable region of Heavy chain).