This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Chemotherapy, Subject name: Pharmacology
Tetracyclines inhibit protein synthesis by: 
Select and explain. 
A. Inhibition of initiation and misreading of mRNA, B. Binding to 30 S subunt and inhibiting the binding of aminoacyl-RNA to A site, C. Inhibiting peptidyl transferase activity, D. Inhibiting translocation
B: Binding to 30 S subunt and inhibiting the binding of aminoacyl-RNA to A site
Answer: B: Binding to 30 S subunt and inhibiting the binding of aminoacyl-RNA to A site 
Explanation: The tetracyclines are primarily bacteriostatic; inhibit protein synthesis by binding to 305 ribosomes in susceptible organism. Subsequent to such binding, attachment of aminoacyl-t-RNA to the mRNA-ribosomc complex is interferred with. ESSENTIALS OF MEDICAL PHARMACOLOGY page no. 734