This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Pharmacology
Buprenorphine paial agonist at which opioid receptor? 
Select and explain. 
A. Mu, B. Kappa, C. Delta, D. Lambda
A: Mu
Answer: A: Mu 
Explanation: Buprenorphine is paial agonist on mu receptor and antagonist at Kappa receptor. REF : katzung pharmacology : 14th ed