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': 'Which of the following shapes of the palatal vault is most favourable for lateral stability? \nSelect and explain. \nA. V shape, B. U shape, C. Flat, D. (B) & (C)', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]