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': 'Graft used in infra inguinal by pass is - \nSelect and explain. \nA. PTFE, B. Dacron, C. Autologous vein, D. Autologous artery', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]