This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
[{'content': 'Border moulding material should not be removed over the posterior palatal seal because: \nSelect and explain. \nA. In enhances the posterior palatal seal., B. It serves as a guide for positioning the tray., C. It prevents aspiration of the impression material., D. All of the above.', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]