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': "Most serious complication of Paget's disease: \nSelect and explain. \nA. Osteochondroma., B. Osteosarcoma., C. Osteopetrosis., D. Osteitis deformans.", 'role': 'user'}, {'content': 'Answer: B \nExplanation: Development of osteosarcoma is the most serious complication of paget’s disease or osteitis deformans.', 'role': 'assistant'}]