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': 'Drug which acts by binding to B site in prokaryotes: \nSelect and explain. \nA. Actinomycin-D, B. Chloramphenicol, C. Puramycin, D. Penicillin', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Chloramphenicol', 'role': 'assistant'}]