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 drug is not metabolized by liver : 
Select and explain. 
A. Flunitrazepam, B. Diazepam, C. Oxazepam, D. Nitrazepam
C: Oxazepam
Answer: C: Oxazepam 
Explanation: None