I'll give you a question, please answer with step-by-step reasoning process.
Committing the murder wore on the man, because of his what he swore he could still hear the man's heart beating?\nOptions:\n- great sorrow\n- stethoscope\n- guilty conscience\n- find god\n- go to jail

guilty conscience
When you have committed murder of someone, you can't forget it easily.

Hearing heartbeats of murdered person is a sign that you are feeling guilty conscience.

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Final answer: guilty conscience