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': 'Preferred material for femoro popliteal bypass- \nSelect and explain. \nA. Dacron, B. PTNE, C. Saphenous vein, D. Gortex', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]