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: outdoor sport activity 
Words: hiking, climbing, mice, fish, row

Answer: mice


Question: Category: boats 
Words: head, hull, knockout, deck, dock

Answer: knockout


Question: Category: chocolate food 
Words: loosen, chocolate, fudge, brownie, tart

Answer:
loosen