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': 'Lamina dura is: \nSelect and explain. \nA. Radiographic appearance of bundle bone, B. Alveolar bone proper, C. Cribriform plate, D. All the above', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]