All characters of Blood thymic barrier except

Correct Answer: C

Rationale: Blood-thymic barrier has continuous endothelium and thick basement , protects immature T-cells ; T-lymphocytes are in both cortex and medulla, but immature are in cortex (C is incorrect).

Correct Answer: C

Rationale: Macrophages engulf pathogens and fuse phagosomes with lysosomes to destroy them ; cytokine production and direct killing are secondary roles.

Correct Answer: A

Rationale: APCs (antigen-presenting cells) activate T cells ; killing and antibody production are other cell roles, not repair .

Correct Answer: B

Rationale: iTreg cells produce IL-10 and TGF-β to suppress immunity ; CD8+ , NK , and neutrophils don't.

Correct Answer: D

Rationale: Hair color and texture don't defend against disease; species resistance , phagocytosis , and interferon are nonspecific defenses.