White pulp of spleen: Contains predominantly lymphocytes.

Correct Answer: A

Rationale: White pulp is primarily composed of lymphocytes, involved in immune responses.

Correct Answer: C

Rationale: Medullary sinuses are spaces between trabeculae and medullary cords in lymph nodes.

Correct Answer: A

Rationale: White pulp branches into penicillar arterioles in red pulp.

Correct Answer: D

Rationale: Thymulin enhances various T-cell functions.

Correct Answer: C

Rationale: Hassall's corpuscles increase with age ; they're in medulla , surrounded by reticular cells not lymphocytes , and are acidophilic .