The answer to your question would be that the sentence that contains an error in pronoun-antecedent agreement is "Everyone should do their own work" (C).
Explanation:
The sentence above is an example of the use of singular <em>they. </em>Singular<em> they </em>is the use of of the pronoun they or any of its derivative forms (their, theirs, them, themselves) as a gender-neutral singular pronoun. This typically occurs with an unspecified antecedent, such as the one in the sentence in question (everyone).