Given a set of five words, generate the word from the set that does not belong (i.e. is the least relevant) with the other words. Words are separated by commas.

[Q]: recruit, replace, sack, heat, fire
[A]: heat

[Q]: hot, classy, pretty, fine, probation
[A]: probation

[Q]: unflappalbe, mild, ethical, positive, cool
[A]:
mild