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': 'Hair-on end appearance is seen in – \nSelect and explain. \nA. Thalassemia, B. Sickle cell anemia, C. Hemochromatosis, D. Megaloblastic anemia', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Hair on end appearance is characteristically and most commonly seen in thalassemia because marrow hyperplasia is more marked in this than other anemia.\nSickle cell anemia is the 2nd most common cause (after thalassemia).', 'role': 'assistant'}]