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: type of sandwich 
Words: open-faced, hero, club, discothek, hamburger
answer:
discothek


question:
Category: employment activity 
Words: pay, instruct, heat, fire, scold
answer:
heat


question:
Category: boxing terminology 
Words: tko, ring, corner, hearts, deck
answer:

hearts