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 ratio of upper anterior facial height and lower anterior facial height in normal occlusion cases is \nSelect and explain. \nA. 60 :\t40, B. 45 :\t55, C. 55 :\t45, D. 40 :\t60', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]