Which sentence contains a grammatical error?

The sentence in question is grammatically correct. It employs proper subject-verb agreement and maintains parallel structure within the list of items (book, pencil, and paper) that each student needs. This structure ensures clarity and coherence in the sentence. On the other hand, the other options are also correct grammatically; B is an imperative sentence with a clear, direct command, C employs exclamation correctly to convey excitement or emphasis, and D is a standard interrogative sentence. Since option A does not contain a grammatical error, the correct response would indeed not be A as understood initially.