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': 'Which instrument is used first \nSelect and explain. \nA. Barbed broach, B. K file, C. H file, D. Any one of the above can be used', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]