This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anti Microbial, Subject name: Pharmacology
[{'content': 'Which of the following drug acts against Pseudomonas \nSelect and explain. \nA. Piperacillin, B. Methicillin, C. Nafcillin, D. Cloxacillin', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Piperacillin Penicillins effective against PseudomonasPiperacillinMezlocillinTicarcillinCarbenicillinList of other Antipseudomonal have already been given. (May 2003, pharma Q. No. 53)Methicillin, Nafcillin and cloxacillin are penicillinase resistant penicillins", 'role': 'assistant'}]