The spleen's primary immune function is to:

Correct Answer: B

Rationale: The spleen filters blood for pathogens; T cells mature in thymus, lymph is from nodes, antibodies aren't stored.

Correct Answer: B

Rationale: Thymosin aids T cell maturation; insulin is pancreas, cortisol and adrenaline are adrenal.

Correct Answer: C

Rationale: Natural passive is from breast milk; active (A, B) involves own response, artificial passive is injected.

Correct Answer: B

Rationale: Secondary lymphatic nodules form following antigen-dependent differentiation, not antigen-independent, which occurs in primary lymphoid organs like the thymus.

Correct Answer: A

Rationale: Lymph enters via afferent vessels , flows into the subcapsular sinus , passes through paratrabecular to medullary sinuses , and exits via efferent vessels , filtering pathogens along the way.