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': 'File with R phase technology \nSelect and explain. \nA. Protaper, B. Wave one, C. Twisted, D. Race', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]