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': 'The posterior palatal seal for a maxillary complete denture: \nSelect and explain. \nA. Is placed immediately posterior to the vibrating Line, B. placed immediately anterior to the vibrating tine, C. Is not necessary if a metal base is made, D. Will vary in outline and depth according to the palatal form', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]