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: animal 
Words: walk, flap, fish, fly, bats

Answer: flap


Question: Category: ocean 
Words: current, data sets, main, sea, wave

Answer: data sets


Question: Category: outdoor sport activity 
Words: wrestle, fish, iguana, hiking, hunt

Answer:
iguana