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.

Q: Category: baby animals 
Words: cub, identity, buck, fawn, kid

A: identity
****
Q: Category: bird 
Words: digger, heron, crane, mallet, sandpiper

A: digger
****
Q: Category: accomodation 
Words: house, flat, plain, level, studio

A:
plain
****