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: Medicine
[{'content': 'Iron overload occurs in all, except - \nSelect and explain. \nA. Thallassemia, B. Myelodysplastic syndrome, C. Polycythemia vera, D. Sideroblastic anaemia', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]