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.
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Question: Category: secretary duty 
Words: support, type, file, software, answer

Answer: software


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

Answer: discothek


Question: Category: outdoor sport activity 
Words: hike, kayak, swim, dolphin, fish

Answer:
dolphin