This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Skeletal System, Subject name: Radiology
[{'content': 'Crew cut appearance on X ray skull is seen in: \nSelect and explain. \nA. Thalassemia, B. Megaloblastic anemia, C. Autoimmune hemolytic anemia, D. Ultrasonography', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. A. ThalassemiaCrew cut appearance in thalassemia occurs due to expansion of the marrow on account of extra-medullary hemapoiesis.The widened diploic spaces on X-ray skull lateral view appear as Crew cut or hair on end appearance.', 'role': 'assistant'}]