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.
--------
Question: Category: direction 
Words: kind, descending, down, opposite of up, flat

Answer: kind


Question: Category: physical property 
Words: fat, area, ugly, capacitance, calcium

Answer: calcium


Question: Category: emotional status 
Words: arrest, alert, fine, alright, calm

Answer:
arrest