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
Most common cause of Budd Chiari syndrome is: 
Select and explain. 
A. Idiopathic, B. Valves in hepatic veins, C. Hepatocellular carcinoma, D. Thrombosis of hepatic veins
D: Thrombosis of hepatic veins
Answer: D: Thrombosis of hepatic veins 
Explanation: Answer is D (Thrombosis of hepatic veins) Most common cause of Budd Chiari Syndrome is hepatic vein obstruction Its the common cause of hepatic vein obstruction causing Budd Chiari Syndrome is 'thrombosis of hepatic veins'.