Given a set of five words, generate the word from the set that does not belong (i.e. is the least relevant) with the other words. Words are separated by commas.

Q: dump truck, tackle, crane, duck, mallet

A: dump truck
****
Q: file, keys, document, fax, ram

A: fax
****
Q: signal, sea, current, drink, belated

A:
belated
****