Antibody Diversity Is Generated by Multiple Mechanisms, Each of Which $\kappa$

Multiple Choice

Antibody diversity is generated by multiple mechanisms, each of which contributes to the generation of antibodies with up to 10¹¹ different amino acid sequences in their antigen-binding sites. Several of these mechanisms involve changes in the DNA sequences encoding the antibody heavy and light chain proteins. One mechanism that does not rely on changes to the DNA within the immunoglobulin heavy and light chain gene loci is, instead, dependent on:

A) The contributions of amino acids from both the heavy chain and the light chain to form the antigen-binding site
B) The random usage of V, D, and J gene segments to form the heavy chain V region sequence
C) The random usage of $\kappa$ light chains versus $\lambda$ light chains to pair with the heavy chain
D) The activity of TdT to add random nucleotides at the junctions between the V, J, and D region sequences
E) The fact that heavy chain V regions contain an extra gene segment encoded by the D region compared to light chain V regions