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': "Lacunar skull is a radiological feature of \nSelect and explain. \nA. Paget's disease, B. Eosinophilic granuloma, C. Fibrous skull, D. Arnold chiari malformation.", 'role': 'user'}, {'content': "Answer: D \nExplanation: Lacunar skull - Arnold chiari malformation.\nCotton wool skull - Paget's disease.\nGeographic skull - Eosinophilic granuloma.", 'role': 'assistant'}]