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
Lacunar skull is a radiological feature of 
Select and explain. 
A. Paget's disease, B. Eosinophilic granuloma, C. Fibrous skull, D. Arnold chiari malformation.
D: Arnold chiari malformation.
Answer: D: Arnold chiari malformation. 
Explanation: Lacunar skull - Arnold chiari malformation.
Cotton wool skull - Paget's disease.
Geographic skull - Eosinophilic granuloma.