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]: mallet, goose, geese, hike, duck
[A]: hike


[Q]: valley, house, cabin, squashed, flat
[A]: valley


[Q]: common, combined, tough, firm, corporation
[A]:
tough