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': 'In root canal treatment, the canal orifices are located\nby: \nSelect and explain. \nA. Endodontic excavator, B. DG-16 Endodontic explorer, C. C+ file, D. H-file', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]