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
Which of the following opioid can be given intranasally? 
Select and explain. 
A. Tramadol, B. Pethidine, C. Butorphanol, D. Buprenorphine
C: Butorphanol
Answer: C: Butorphanol 
Explanation: Butorphanol is full agonist at kappa & antagonist at μ receptor that can be given intranasally.