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': 'Surface of NiTi wire is \nSelect and explain. \nA. Rougher than beta titanium wire, B. Rougher than stainless steel wire, C. Both of the above, D. None of the above', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]