"Tell Susan its Marys turn not hers" A.Tell Susan it's Mary's turn,not hers. B. Tell Susan its Marys ' turn not hers. C.Tell Susan it's Marys' turn not hers. C Tell Susan its Mary's turn ,not hers.
A. is the correct answer. (Grammatically) Apostrophes are used as either a substitute for is or for showing possession. is- "Tell Susan it's.." possession- " Mary's turn not hers."
