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': 'Kirkland and orban knives are used for \nSelect and explain. \nA. Curettage, B. Gingivectomy, C. Root planning, D. Scaling', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]