All of the following act as gaseous neurotransmitters except

(A) Oxygen # TYPES OF NEUROTRANSMITTERS:> There are many different ways to classify neurotransmitters. Dividing them into amino acids, peptides, and monoamines is sufficient for some classification purposes.> Major neurotransmitters:> Amino acids: glutamate, aspartate, D-serine, Gamma-aminobutyric acid (GABA), glycine> Monoamines and other biogenic amines: dopamine (DA), norepinephrine (noradrenaline; NE, NA), epinephrine (adrenaline), histamine, serotonin (SE, 5-HT)> Peptides: somatostatin, substance P, opioid peptides> Others: acetylcholine (ACh), adenosine, anandamide, nitric oxide, etc..