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
[{'content': 'Solitary eosinophilic granuloma, commonest in the- \nSelect and explain. \nA. Femur, B. Skull, C. Radius, D. Lumbar vertebra', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]