Which of the following can be attributed to the clonal selection hypothesis of antibody formation?

• A. Plasma cells make generalized antibody.
• B. B cells are preprogrammed for specific antibody synthesis.
• C. Proteins can alter their shape to conform to antigen.
• D. Cell receptors break off and become circulating antibody.

Answer: (B)

The idea being tested is that the antibody response comes from selecting and expanding B cells that already carry a receptor specific for the encountered antigen. In clonal selection, each B cell has a unique antibody receptor due to genetic rearrangements, giving a diverse preexisting repertoire. When a particular antigen appears, only the B cells with receptors matching that antigen are activated. Those specific clones then proliferate and differentiate into plasma cells that secrete antibodies of that exact specificity, along with memory B cells for quicker responses in the future. That is why the statement about B cells being preprogrammed for producing a specific antibody best matches this hypothesis.

The other ideas don’t fit as neatly with clonal selection. Plasma cells producing generalized antibodies would lack the required specificity; clonal selection explains antigen-driven, specific antibody production. The notion that proteins alter their shape to fit antigen describes a general concept of conformational adjustments at binding sites, not how the immune system generates specific antibodies. And antibodies aren’t produced by receptors breaking off the B cell; plasma cells actively secrete antibodies, not shed cell-surface receptors.