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': 'Scaling stroke? \nSelect and explain. \nA. Shorty & powerful pull stroke, B. Moderate to light pull stroke, C. Moderate to light push stroke, D. A long pulling stroke', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]