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': 'A double bar anterio posterior palatal major connector is indicated when \nSelect and explain. \nA. A single palatal bar is not rigid, B. Maximum palatal support is needed, C. High vault palate is present, D. All of the above', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]