This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Introduction to Central Nervous System, Subject name: Physiology
Low molecular weight neurotransmitters are all except: 
Select and explain. 
A. Glutamate, B. GABA, C. Dopamine, D. Orexins
D: Orexins
Answer: D: Orexins 
Explanation: Low molecular weight neurotransmitters: (Small molecule transmitter) Glutamate GABA Ach NA Dopamine High molecular weight neurotransmitters: (Large molecule transmitter) NP Y Orexins Opioid CA