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': 'Poal hypeension is defined as hepatic venous pressure gradient more than: \nSelect and explain. \nA. 1 mm Hg, B. 5 mm Hg, C. 10 mm Hg, D. 20 mm Hg', 'role': 'user'}, {'content': "Answer: B \nExplanation: Poal hypeension is defined as the elevation of the hepatic venous pressure gradient (HVPG) to >5 mmHg. Poal hypeension is caused by a combination of two simultaneously occurring hemodynamic processes. Ref: Harrison's principle of internal medicine 17th edition, chapter 302.", 'role': 'assistant'}]