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
Therapeutic drug monitoring is required for: March 2010 
Select and explain. 
A. Sulfonamides, B. Metformin, C. Cycloserine, D. Gentamycin
D: Gentamycin
Answer: D: Gentamycin 
Explanation: Ans. D: Gentamycin