This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Opioids, Subject name: Pharmacology
Opioid agonist-antagonist is : 
Select and explain. 
A. Pethidine, B. Pantazocine, C. Buprenorphine, D. Methadone
B: Pantazocine
Answer: B: Pantazocine 
Explanation: Ans. is 'b' Pentazocine Opioid Agonist Antagonists Not used as analgesic - Nalorphine* levallorphan* Used as analgesic - Pentazocine* NalbuphinePure Opioid Antagonists :NaloxoneNaltrexonePartial weak agonistsBuprenorphineButorphanol