The innate immune response together with antibodies are generally not effective at clearing infections established by pathogens that replicate inside host cells. The evolution of T cells has provided a means for the immune response to 'see' intracellular infections based on the ability of T cells to:

Correct Answer: D

Rationale: T cells detect intracellular pathogens via MHC-peptide complexes ; cytokines , interferon , or inflammation are indirect.

Correct Answer: A

Rationale: Histamine causes vasodilation, increasing blood flow to the injury site, not blocking pollen responses, converting to histidine, or raising blood pressure.

Correct Answer: D

Rationale: Monoclonal antibodies are identical, binding one antigen, not a mix of different antibodies, making D false; others are true applications.

Correct Answer: B

Rationale: Neutrophils are the most abundant WBCs in blood, excelling in phagocytosis, not antigen presentation (DCs) or viral cell killing (NK cells).

Correct Answer: B

Rationale: Both TCRs and BCRs activate via antigen binding to variable regions, unlike binding sites (BCR: 2, TCR: 1), chains (TCR: αβ, BCR: heavy/light), or secretion (BCR only).