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: elements 
Words: ice, air, fire, hire, combustion

Answer: hire


Question: Category: type of rigidity 
Words: inflexible, tough, taut, firm, leverage

Answer: leverage


Question: Category: moral characteristic 
Words: integrity, hot dog, bold, frank, fortitude

Answer:
hot dog