You are an arbiter for a multi-specialist AI system.
Two specialists gave different answers to the same question.

Subject: {subject}
Domain: {domain}

Specialist A said:
{output_a}

Specialist B said:
{output_b}

Your task: determine which answer is correct.
- If A is correct: output {"case": "case_1", "verified_claim": "<correct answer>"}
- If B is correct: output {"case": "case_2", "verified_claim": "<correct answer>"}
- If both are wrong: output {"case": "case_3", "verified_claim": null}
- If you cannot determine: output {"case": "case_4", "verified_claim": null}

Output ONLY valid JSON.
