Use reasoning to lead to the answer of the following question:
John had a gun but he set it aside. It wasn't helpful. He needed to build a fire. Why did he need a fire?\nOptions:\n- murder\n- warm hands\n- harm\n- warm up\n- park
 Reasoning process:
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Person may need fire to warm up himself. Gun cannot be used to build fire. Therefore, the final answer is warm up.
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