Which one of the following statements regarding somatic hypermutation (SHM) and class switch recombination (CSR) is correct?

Question

Answer

SHM and CSR are untargeted events, occurring at random within immunoglobulin loci

Answer

SHM and CSR require different activities of  activation induced cytidine deaminase  (AID)

Answer

Activation induced cytidine deaminase (AID) is required for both SHM and CSR

Answer

IgM antibodies are always higher affinity than IgG antibodies recognising the same antigen because each secreted IgM antibody is a pentamer

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