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: geographical property 
Words: paved, even, hill, level, flat

Answer: even


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

Answer: knockout


Question: Category: animal 
Words: walk, bee, fly, run, bus

Answer:
bus