This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Abdomen & Pelvis, Subject name: Anatomy
[{'content': 'Portal vein starts at level of? \nSelect and explain. \nA. L2, B. L3, C. L4, D. L5', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. A L2Ref: Netter's Clinical Anatomy, 3rd ed. pg. 202* Portal vein starts at level of L2 vertebra and is formed by junction of superior mesenteric vein and splenic vein. It is 8 cm long and lies behind the neck of pancreas.* Normal portal vein pressure is 5-10 mm Hg.", 'role': 'assistant'}]