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.

[EX Q]: Category: secretary duty 
Words: answer calls, image, organize, file, correspondence
[EX A]: image

[EX Q]: Category: outdoor sport activity 
Words: dog, swim, hike, hiking, fish
[EX A]: dog

[EX Q]: Category: elements 
Words: let go, ground, ice, air, fire
[EX A]:
let go