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: Pathology
Solitary eosinophilic granuloma, commonest in the- 
Select and explain. 
A. Femur, B. Skull, C. Radius, D. Lumbar vertebra
B: Skull
Answer: B: Skull 
Explanation: None