instruction:
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: employment activity 
Words: ban, fire, empower, sack, ground
answer:
ground


question:
Category: geographical property 
Words: mountain, flat, hill, mansion, plain
answer:
mansion


question:
Category: physical activity 
Words: plummet, trip, equinox, lift, fall
answer:

equinox