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
[{'content': 'Opioid available as nasal spray formulation is ? \nSelect and explain. \nA. Tramadol, B. Codiene, C. Butorphanol, D. Buprenorphine', 'role': 'user'}, {'content': "Answer: C \nExplanation: Ans. is'c'i.e., Butorphanol [Ref: KDT 7h/e p. 482)Butorphanol - Nasal spray (Stadol)", 'role': 'assistant'}]