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': 'A patient comes in dental office for routine dental check up. His upper central incisor which is root canal treated 6 months ago, shows a Periapical radiolucency, but the patient has no previous radiographs of the lesion. Treatment at this time: \nSelect and explain. \nA. No treatment, observe, B. Redo the RCT, C. Make a Post and Core, D. Do apicoectomy', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]