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': 'In preparing a primary molar for a stainless steel crown,\nthe surface requiring the least amount of reduction is \nSelect and explain. \nA. Occlusal, B. Lingual, C. Mesial, D. Facial', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]