You will be given a trivia clue, and the category it belongs to. You should answer with the best answer that belongs in the category and is described by the clue. For consistency, answers should be in all lower cased letters.
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Question: Category: CONFUSE US 
Clue: Affluent means wealthy: effluent refers to waste in this state of matter

Answer: liquid


Question: Category: SPORTS SCORES 
Clue: In volleyball, only the side who did this at the beginning of play can score a point

Answer: serve


Question: Category: BANDS IN OTHER WORDS 
Clue: Portals

Answer:
the doors