Use reasoning to lead to the answer of the following question:
Where is the best way to store personal knowledge?\nOptions:\n- university\n- encyclopedia\n- book\n- safe\n- head
 Reasoning process:
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Head is the upper part of the human body, or the front or upper part of the body of an animal, typically separated from the rest of the body by a neck, and containing the brain, mouth and sense organs. Head is the best way to store personal knowledge. Therefore, the final answer is head.
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