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
Which of the following acts by inhibition of 30 S ribosome - 
Select and explain. 
A. Tetracycline, B. Chloramphenical, C. Erythromycin, D. Penicillin
A: Tetracycline
Answer: A: Tetracycline 
Explanation: Ans. is 'a' i.e., Tetracycline