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: Answer is C (Paroxymal nocturnal hemoglobinuria) P'sH is the most common cause of iSudd Chiral syndrome amongst the options provided. Most common cause of Budd chiari syndrome is - thrombosis of hepatic veinQ This is seen in the setting of : - polycythemia rubra veraQ - myeloproliferative syndromeQ - Paroxysmal nocturnal hemoglobinuriaQ - Oral contraceptive use - Hyercoagulable states It may also result from obstruction of venacava.Q This may be seen in the setting of : - invasion of IVC by tumor such as hepatocellular carcinoma. - Idiopathetic membranous obstruction of IVC is the most common cause of this syndrome in Japan.