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': 'Cross resistance to macrolides is because: \nSelect and explain. \nA. Efflux of drug out of the cell by pump, B. Induction of enzyme that hydrolyzes macrolides, C. Methylation of 50s ribsome, D. None of the above', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Methylation of 50s ribosome can lead to cross resistance in macrolides, lincosamides and streptogrammins.', 'role': 'assistant'}]