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.

Category: outdoor sport activity 
Words: whale, fish, raft, hiking, kayak
whale

Category: secretary duty 
Words: answer calls, file, correspondence, document, fax
document

Category: emotional status 
Words: emotional supports, south, melancholy, unhappy, down

south