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
Border moulding material should not be removed over the posterior palatal seal because: 
Select and explain. 
A. 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.
D: All of the above.
Answer: D: All of the above. 
Explanation: None