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': 'Maxillary 1st molar has MB2 in: \nSelect and explain. \nA. 41% of cases, B. 84% of cases, C. 60% of cases, D. 30% of cases', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]