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: police punishment 
Words: ticket, comfortable, prime, custody, fine

Answer: comfortable


Question: Category: elements 
Words: fire, retire, ice, air, earth

Answer: retire


Question: Category: boats 
Words: hull, bow, deck, tko, dock

Answer:
tko