During the development of B cells, the Ig gene segments are rearranged and brought next to each other to form a contiguous functional gene (somatic recombination). The complex of enzymes involved in somatic recombination in lymphocytes is called:

Correct Answer: C

Rationale: V(D)J-recombinase, including RAG-1 and RAG-2, facilitates somatic recombination in B and T cells.

Correct Answer: C

Rationale: Somatic hypermutation increases affinity in B cells but not in T cells.

Correct Answer: C

Rationale: CD4 and CD8 are co-receptors that enhance signal transduction in T cells.

Correct Answer: D

Rationale: MHC class II includes six genes: HLA-DP, DQ, and DR, each with alpha and beta chains.

Correct Answer: D

Rationale: Insulin-dependent diabetes mellitus is associated with HLA-DR4.