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
All the following drugs act on ionic channels except: 
Select and explain. 
A. Nicotine, B. Insulin, C. Glibenclamide, D. Diazepam
B: Insulin
Answer: B: Insulin 
Explanation: None