Final answer:
In early pro-B cells, the process is known as DJ rearrangement, and it occurs on both chromosomes. This genetic recombination of B cells contributes to the immune system's diversity by allowing each antibody to have a unique antigen-binding site.
Step-by-step explanation:
In early pro-B cells, there is DJ rearrangement. This process occurs on both chromosomes. The correct answer to the given question is (b) DJ; Both. When B cells undergo maturation, an enzyme called DNA recombinase is responsible for randomly excising DNA segments. For the light chain gene, it excises V (variable) and J (joining) segments and later splices one V segment to one J segment. This contributes to the diversity found in immunoglobulins or antibodies as every B cell produces a unique variable chain capable of binding a different antigen. The heavy chain gene, which involves V, D (diversity), and J segments, also goes through a recombination process, further enhancing the potential diversity of the immune response.
The unique combinations of these gene segments lead to a large array of possible antigen-binding sites, with DNA rearrangement occurring at the DNA level before transcription and translation processes that result in a mature antibody. Hence, the genetic recombination providing antibody diversity is a significant aspect of the adaptive immune system's ability to recognize and respond to a multitude of microbial epitopes.