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': 'What is the most common cause for Budd chiary syndrome- \nSelect and explain. \nA. Right ventricular failure, B. PNH, C. Valve in hepatic veins, D. Polycythemia vera', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Answer is D (Polycythemia vera) Polycythemia vera is the most common cause for Budd chiral syndrome amongst the options provided.', 'role': 'assistant'}]