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: Pharmacology
[{'content': 'The following is not a penicillinase resistant penicillin- \nSelect and explain. \nA. Methicillin, B. Ampicillin, C. Oxacillin, D. Nafcillin', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. is b i.e., Ampicillin', 'role': 'assistant'}]