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 drug is used only topically? 
Select and explain. 
A. Streptomycin, B. Neomycin, C. Gentamycin, D. Netilmycin
B: Neomycin
Answer: B: Neomycin 
Explanation: None