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': 'Ultrasonic scalers vibrate at approximately \nSelect and explain. \nA. 25000 cycles per second, B. 15000 cycles per second, C. 10000 cycles per second, D. 50000 cycles per second', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]