Which of the following sentences is grammatically correct?

Question

Quizplus · Accepted Answer

This is the only grammatically correct sentence. Their is the third-person plural possessive pronoun.
Knock on the door in case there is someone in their.
The word their is the third-person plural possessive pronoun. In this sentence, the correct word would be there, an adverb that means "at that place."
There convinced Sharon is going to name her baby after her grandfather.
The word there is an adverb that means "at that place." In this sentence, the correct word would be they're, the contraction of they are.
Our van was dirty but they're car looked brand new.
The word they're is the contraction of they are. In this sentence, the correct word would be their, the third-person plural possessive pronoun.

Which of the Following Sentences Is Grammatically Correct