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: fish, hike, hunting, row, dog

Answer: dog


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

Answer: data sets


Question: Category: nutritional value 
Words: heavy, fat, heavy, protein, salt

Answer:
heavy