They are antonyms. Pollute and purify are opposite meanings. Pollute means to ruin or make something unclean, while purify means removing the harmful or dirtiness out of something.
Please state the options / choices so that we can answer your question.
The answer here would be "Acts against the main protagonist to create conflict"
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Answer: Calypso loves Odysseus and wants to make him immortal so he can stay with her and be her husband forever, even though she understands that he doesn't love her back and wants to return to Penelope.
Explanation: