Which sentence contains an incorrect possessive form?

A.Everyone's coats are in the hall closet.

B.The cat has been chasing its tail all morning.

C.The most creative costumes of the night are theirs'.

D.Is that somebody's phone on the floor?

Respuesta :

The sentence that contains an incorrect possessive form is C) The most creative costumes of the night are theirs'.
The correct option is theirs, there should be no apostrophe after the word.