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': 'Most widely used spring-loaded surveyor is: \nSelect and explain. \nA. Ney surveyor, B. Jelenko surveyor, C. WillIams surveyor, D. None of the above', 'role': 'user'}, {'content': 'Answer: B \nExplanation: The most widely used surveyors are the Ney and the Jelenko.\nBoth of these are precision made instruments.\nThey differ principally in that the Jelenko arm swivels, whereas the Ney arm is fixed.', 'role': 'assistant'}]