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
At mu receptor, buphrenorphine is? 
Select and explain. 
A. Paial agonist, B. Paial antagonist, C. Complete agonist, D. Complete antagonist
A: Paial agonist
Answer: A: Paial agonist 
Explanation: Ans. is 'a' i.e., Paial agonist