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': 'All are exploring instruments for a root canal except: \nSelect and explain. \nA. DG-16, B. JK-17, C. CK-17, D. JW-17', 'role': 'user'}, {'content': "Answer: B \nExplanation: The DG-16 endodontic explorer is used to identify canal orifices and to determine canal angulation.\nThe CK-17 endodontic explorer serves the same purpose, but it's thinner, stiffer tip can be useful for identifying calcified canals.\nMicro JW-17 -\xa0Thin Canal Explorer, Double-Ended, Single instrument.\n\nJK-17\xa0 - Dental explorer or sickle probe.", 'role': 'assistant'}]