This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.N.S, Subject name: Pharmacology
[{'content': 'Buprenorphine is partial agonist of \nSelect and explain. \nA. Mu (u) receptor, B. Delta (d) receptor, C. Kappa (k) receptor, D. Sigma (s) receptor', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Mu (m) receptor BuprenorphineReceptor p(mu) - Partial agonistK (kappa) - Antagonist (moderate) d (delta) - Also know -Buprenorphine produces ceiling effect", 'role': 'assistant'}]