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 : \nSelect and explain. \nA. DNA gyrase inhibitors, B. Bind to 30 S unit of ribosomes and inhibit protein synthesis, C. Bind to bacterial cell membrane, D. Bind to tetra hydro folate reductase', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]