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': 'Not seen in OSTEOPETROSIS: \nSelect and explain. \nA. Pancytopenia, B. Delayed healing of fractures, C. Compression of cranial nerve, D. Osteomyelitis of mandible', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. Delayed healing of fractures', 'role': 'assistant'}]