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 optimal flow rate of coolant for sonic and ultrasonic subgingival scaling is \nSelect and explain. \nA. 1-11 ml/min, B. 14-23 ml/min, C. 24-32 ml/min, D. 34-40 ml/min', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]