What is the term for the lymph node's outer region?

Correct Answer: B

Rationale: The cortex is the outer region; medulla is inner, hilum is entry, sinus is channel.

Correct Answer: A

Rationale: Antibodies trigger the classical complement pathway; pathogens trigger alternative, cytokines signal, histamines inflame.

Correct Answer: C

Rationale: T-helper cells activate others; killing is cytotoxic T, antibodies are B cells, phagocytosis is macrophages.

Correct Answer: B

Rationale: The alternative pathway is pathogen-triggered; antibodies are classical, cytokines signal, histamines inflame.

Correct Answer: D

Rationale: Immunodeficiency is genetic weakness; allergy and hypersensitivity are overreactions, autoimmunity is self-attack.