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': 'Motion of use for reamers is \nSelect and explain. \nA. Pulling or rasping, B. Linear to and fro, C. Penetration retracton and rotation, D. Circumferential', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]