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
One of the followig opioid derivatives is a paial agonist as well as antagonist- 
Select and explain. 
A. Buprenorphine, B. Naloxone, C. Nalorphine, D. Naltrexone
C: Nalorphine
Answer: C: Nalorphine 
Explanation: Ans. is 'c' i.e., Nalorphine