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: Surgery
Budd Chiari syndrome is due to thrombosis of ? 
Select and explain. 
A. Infra renal IVC, B. Renal pa of IVC, C. Superior mesentric vein thrombosis, D. Hepatic veins
D: Hepatic veins
Answer: D: Hepatic veins 
Explanation: Ans. is 'd' i.e., Hepatic veins