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': 'Phentom tooth pain is persistent pain after RCT, more than \nSelect and explain. \nA. 2 months, B. 3 months, C. 5 months, D. 6 months', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]