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': 'Venous thrombosis In patients with paroxysmal nocturnal hemoglobinuria is observed in \nSelect and explain. \nA. Cerebral veins, B. Leg veins, C. Intrabdominal veins, D. Axillary vein', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Answer- C. Intrabdominal veinsVenous thrombosis is an inconstant but severe clinical manifestation of P.N.H.Thrombosis occcurs due to absence of CD59 which k a membrane attached proteinThrombosis usually occurs in abdominal veins. Intra-abdominal yeins are the most common site of thromosis in P.N.H.', 'role': 'assistant'}]