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': 'For prophylaxis of deep vein thrombosis used is ? \nSelect and explain. \nA. Warfarin, B. Heparin, C. Pneumatic shocks garment, D. Graded stocking', 'role': 'user'}, {'content': "Answer: B \nExplanation: Answer is 'b' i.e. Heparin", 'role': 'assistant'}]