This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Poal Hypeension, Subject name: Surgery
[{'content': 'Normal poal vein pressure is: \nSelect and explain. \nA. <3 mm Hg, B. 3-5 mm Hg, C. 5-10 mm Hg, D. 10-12 mm Hg', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Poal Pressure Normal Poal vein pressure: 5-10 mm Hg Variceal formation occurs when poal pressure is >10 mm Hg Variceal bleeding occurs when poal pressure is >12 mm Hg.', 'role': 'assistant'}]