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.

Category: emotional status 
Words: ashamed, down, emotional upsets, disgusted, ground
ground

Category: elements 
Words: let go, flame, inferno, fire, water
let go

Category: emotional status 
Words: content, hearing, fine, happy, alert

hearing