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': 'Acquired multistep drug resistance can be seen in all except: \nSelect and explain. \nA. Erythromycin, B. Streptomycin, C. Tetracycline, D. Chloramphenicol', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Development of acquired resistance may be due to single-step mutation (as seen with streptomycin\xa0 and rifampicin) or multi-step mutation (erythromycin, tetracycline and chloramphenicol).', 'role': 'assistant'}]