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: Radiology
[{'content': 'The presence of pulp stones on the radiograph of a tooth\nindicates the presence of \nSelect and explain. \nA. Acute pulpitis, B. Acute pulpalgia, C. Chronic periodontitis, D. None of the above', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]