The Array of Potential Antibodies to the Variety of Possible

The array of potential antibodies to the variety of possible antigens is amazing.Which statement explains this development?

A) Mutations in the antibody gene occur within the activated B cells, since they meet the antigen.
B) The existing antibody molecules change their shapes, allowing them to fit with a large number of antigens.
C) There is a shuffling of genes that code for self markers as well as nonself markers, mixing them together and producing reactive lymphocytes to those markers.
D) Recombination of genes coding for the variable regions of immunoglobulins occurs during the developmental stage of lymphocyte production.