The correct answer is D. When we got to our seats, some other fans said the seats were theirs.
Step-by-step explanation:
In sentences, possessive pronouns such as the words yours, ours, theirs, etc. indicate ownership, usually as they refer back to a noun previously mentioned. Also, these do not require the use of an apostrophe (') as it occurs when a regular noun is used to show possession as in "Carla's house".
From the options, the one that is correct is "When we got to our seats, some other fans said the seats were theirs" because the words "theirs" and "ours" correctly show ownerships of the seats and this option does not include the use of the apostrophe, which is incorrect in this context.