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': 'An endodontic reamer is least likely to fracture when inserted in a: \nSelect and explain. \nA. Dry, clean canal, B. Wet, clean canal, C. Wet, debris laden canal, D. Dry, debris laden canal', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Irrigants perform physical and biologic functions. Dentin shavings get removed from canals by irrigation.\nThus, they do not get packed at the apex of root canal.\nInstruments do not work properly in dry canals.\xa0\nTheir efficiency increases by use in wet canals.\xa0\nInstruments are less likely to break when canal walls are lubricated with irrigation.', 'role': 'assistant'}]