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': 'A thin radio-opaque line running around the curvature of root in IOPA is \nSelect and explain. \nA. Lamina dura, B. Lamina Propria, C. Lamina Limitans, D. Lamina densa', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]