You are designing a cascade for an internal IT help assistant: the smallest tier answers first, and some requests escalate to a larger tier. Answers must be valid JSON with required fields and must cite passages from the retrieved knowledge base. Which two escalation triggers are most appropriate? Select two.

Answer: A and C — The small model's output fails schema validation for the required fields / A passage the answer cites does not match any passage that was retrieved

(a) and (c) are right: both are observable, verifiable checks that indicate the small model actually failed on this request. (b) relies on self-reported confidence, which isn't well calibrated without validation against labeled data. (d) is a crude proxy for difficulty that would escalate many easy requests and miss short hard ones.