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 offset angle of Gracey curette between the blade and shank is: \nSelect and explain. \nA. 50°, B. 70°, C. 80°, D. 90°', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]