The human lymphatic system consists of all of the following structures except the

Correct Answer: D

Rationale: The pancreas is not part of the lymphatic system, which includes thymus, tonsils, and spleen for immune functions.

Correct Answer: B

Rationale: C3 is central to all pathways (classical, lectin, alternative), cleaved to initiate downstream effects, unlike C9 (MAC), C1q (classical), or C4 (classical/lectin).

Correct Answer: A

Rationale: The antigen-binding site is formed by variable regions of both heavy and light chains, creating specificity.

Correct Answer: D

Rationale: Superantigens nonspecifically overactivate T cells via MHC-TCR bridging, evading specific responses.

Correct Answer: C

Rationale: Anamnestic (memory) response is rapid due to memory cells; effector and intensity are features, but C is specific.