This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Central Nervous system, Subject name: Pharmacology
Which of the following is not an opioid peptide? 
Select and explain. 
A. Beta Endorphin, B. Epinephrine, C. Leu5-encephalin, D. Met5-encephalin
B: Epinephrine
Answer: B: Epinephrine 
Explanation: Beta endorphin, leu-5 encephalin, met-5encephalin are all opiod peptides. Ref KD Tripathi 8th ed.