Which of the following is not associated with mucosal surfaces?

Correct Answer: D

Rationale: White pulp is in the spleen, not mucosal surfaces, unlike goblet cells, lysozyme, and M cells, which protect mucosal barriers.

Correct Answer: A

Rationale: Plasma cells secrete antibodies; T cells and macrophages don't.

Correct Answer: D

Rationale: Lymph is primarily interstitial fluid that has entered lymphatic vessels, similar in composition but with fewer proteins than blood or serum.

Correct Answer: A

Rationale: The alternative complement pathway is nonspecific, unlike IgE binding or specific B-cell responses.

Correct Answer: C

Rationale: B cells activate and differentiate in lymph nodes, producing plasma cells.