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
Commonest cause of Budd Chiari syndrome is - 
Select and explain. 
A. Valve in the IVC, B. Hepatocellular carcinoma, C. Paroxysmal nocturnal hemoglobinuria, D. Renal cell carcinoma
C: Paroxysmal nocturnal hemoglobinuria
Answer: C: Paroxysmal nocturnal hemoglobinuria 
Explanation: None