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': 'Bone within bone appearance is seen in? \nSelect and explain. \nA. CML, B. Osteoporosis, C. Osteopetrosis, D. Bone infarct', 'role': 'user'}, {'content': 'Answer: C \nExplanation: C i.e. Osteopetrosis In osteopetrosis, there is reduced osteoclastic bone resorption resulting in diffuse symmetrical skeleton sclerosis. Also k/a marble bone disease d/t its stone like quality of bones; however the bones are abnormally brittle & fracture like a piece of chalk. It can present radiologically as? Sclerosis of all bones more prominent at base of skullQ. Sclerosis of veebral end plate 1/t characteristic sandwitch or broad stripped (rugby jersey spine) Q Bone in bone appearanceQ d/t sclerotic foci within the bone.', 'role': 'assistant'}]