Which cells are key to the secondary immune response?

Correct Answer: A

Rationale: Memory cells drive faster secondary responses; neutrophils , macrophages , and dendritic are initial responders.

Correct Answer: B

Rationale: T cells undergo negative selection; B cells are in marrow, macrophages and neutrophils don't.

Correct Answer: B

Rationale: Medullary sinuses contain lymph, not blood; blood is found in vascular structures like sinuses of the spleen.

Correct Answer: A

Rationale: The encircled region is a secondary lymphatic nodule, characterized by a germinal center.

Correct Answer: C

Rationale: Afferent vessels enter at the convex surface, efferent vessels and veins exit at the concave hilum of the lymph node.