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': 'Which of the following drugs act against Pseudomonas? \nSelect and explain. \nA. Nafcillin, B. Cloxacillin, C. Methicillin, D. Piperacillin', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]