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 most common is \nSelect and explain. \nA. Sickle cell disease, B. Hereditary spherocytosis, C. G6PD deficiency, D. Cyanotic heart disease', 'role': 'user'}, {'content': 'Answer: A \nExplanation: All of the above causes Hair on end appearance.\nThalassemia major > Sickle cell disease.\nNo Thalassemia major in Options.', 'role': 'assistant'}]