Given a category and a set of five words, find the word from the set that does not belong (i.e. is the least relevant) with the other words in the category. Words are separated by commas.
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Question: Category: chocolate food 
Words: cake, fudge, rich, invent, cream

Answer: invent


Question: Category: boxing terminology 
Words: corner, fold, deck, knockout, level

Answer: fold


Question: Category: ocean 
Words: current, main, wave, do tests, whirlpool

Answer:
do tests