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': "Cocket & Dodd's operation is for \nSelect and explain. \nA. Saphenofemoral flush ligation, B. Subfascial ligation, C. Deep vein thrombosis, D. Diabetic foot", 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]