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': 'Which of the following acts by inhibition of 30 S ribosome - \nSelect and explain. \nA. Tetracycline, B. Chloramphenical, C. Erythromycin, D. Penicillin', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Tetracycline", 'role': 'assistant'}]