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': 'For root resection the choice of therapy is \nSelect and explain. \nA. disto buccal root of upper first molar, B. Mesio buccal root of upper first molar, C. Palatal root of upper first molar, D. Both mesio buccal and disto buccal root', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]