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: animal 
Words: flutter, swim, ant, fly, bats
flutter

Category: bird 
Words: dump truck, pelican, goose, crane, derrick
dump truck

Category: chocolate food 
Words: tart, fudge, truffles, unwarranted, cookies

unwarranted