Which structure connects lymph nodes in a chain?

Correct Answer: A

Rationale: Lymphatic vessels link nodes; blood vessels and nerves don't, and ducts are larger.

Correct Answer: B

Rationale: Thymosin from the thymus aids T cell maturation; insulin is pancreas, adrenaline is adrenal, cortisol is adrenal.

Correct Answer: C

Rationale: Lymph nodes trap pathogens; spleen filters blood, thymus matures T cells, appendix is minor.

Correct Answer: A

Rationale: The marginal zone separates red and white pulp; others (B, C, D) are unrelated.

Correct Answer: C

Rationale: Neutrophils are granulocytes; lymphocytes and dendritic cells are agranulocytes, monocytes become macrophages.