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
A thin radio-opaque line running around the curvature of root in IOPA is 
Select and explain. 
A. Lamina dura, B. Lamina Propria, C. Lamina Limitans, D. Lamina densa
A: Lamina dura
Answer: A: Lamina dura 
Explanation: None