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: nutritional value 
Words: iron, heavy, vitamin c, fat, brittleness
brittleness

Category: shady activities 
Words: replace, unwarranted, pie, fudge, unlicensed
pie

Category: bird 
Words: davit, dump truck, hummingbird, duck, crane

dump truck