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': 'Recommended angle of root end resection is: \nSelect and explain. \nA. 45 degree, B. 0 degree, C. 30 degree, D. 15 degree', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]