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': 'Mechanism of action of quinolones is by? \nSelect and explain. \nA. Inhibiting DHFRase, B. Inhibiting DNA gyrase, C. Inhibiting protein synthesis, D. Inhibiting cell wall synthesis', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]