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': 'Characteristic radiological feature of fibrous dysplasia: \nSelect and explain. \nA. Thickened bone matrix, B. Coical erosion, C. Ground glass appearance, D. Bone enlargement', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. Ground glass appearance', 'role': 'assistant'}]