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: Orthopaedics
[{'content': 'True about fibrous dysplasia (F.D) is \nSelect and explain. \nA. Monostotic FD more commonly seen in femur, B. Polyostotic FD manifests in 3rd decade, C. Biopsy shows chicken wire appearance, D. X-ray shows patchy calcification', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]