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: Medicine
[{'content': 'A patient of known valvular disease requires dental extraction. Pretreatment prophylaxis should be given with: \nSelect and explain. \nA. Tetracycline 1000mg. one hr before surgery, B. Amoxicillin 3g orally one hour before, C. Amoxicillin 1g IM one hour before, D. Benzyl penicillin 12 lakh units 1 hour before', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]