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': 'A patient develops an infection of methicillin-resistant Staphylococcus aureus. Which of the following drug cannot be used to treat the infection: \nSelect and explain. \nA. Vancomycin., B. Cotrimoxazole., C. Cefaclor., D. Ciprofloxacin.', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Cefaclor is a second generation cephalosporin and is not active against MRSA.', 'role': 'assistant'}]