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: social gathering 
Words: club, group, meeting, grilled cheese, convention

Answer: grilled cheese


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

Answer: data sets


Question: Category: animals 
Words: swan, hike, duck, cat, elephant

Answer:
hike