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
[{'content': 'A 20 year old man presents with repeated episodes of hematemesis. there is no history of jaundice or liver decompensation. On examination, the significan findings include moderate splenomegaly and presence of esophageal varices. There is no ascites or peptic ulceration. The liver function tests are normal. What is the most likely diagnosis? \nSelect and explain. \nA. Extrahepatic portal venous obstruction, B. Non cirrhotic portal venous obstruction, C. Cirrhosis, D. Hepatic venous outflow tract obstruction', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]