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: nutritional value 
Words: iron, heavy, vitamin c, fat, brittleness

Answer: brittleness


Question: Category: geographical property 
Words: mountain, flat, hill, mansion, plain

Answer: mansion


Question: Category: aesthetic characteristic 
Words: milky, even, texture, fair, loyal

Answer:
loyal