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 six keys to normal occlusion was introduced by: \nSelect and explain. \nA. Dewey, B. Andrews, C. Tweed, D. Angle', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]