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': 'According to ISO classification powered instruments with high speed rotary can be classified as \nSelect and explain. \nA. Group 1, B. Group 2, C. Group 3, D. Group 4', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]