The choice between "bodies" and "body's" depends on the context in which you are using the word.
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"Bodies" is the plural form of "body," referring to more than one body. For example: "The bodies were found in the forest."
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"Body's" is the possessive form of "body," indicating that something belongs to a body. For example: "The body's response to the medication was swift."
If you provide more context, I can help clarify which form you should use!