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: fish, iguana, canyoning, hamster, horse

Answer: canyoning


Question: Category: police punishment 
Words: prime, fine, jail, suspension, well

Answer: well


Question: Category: geographical property 
Words: flat, mountain, valley, hill, duplex

Answer:
duplex