This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nervous System, Subject name: Physiology
[{'content': 'Inhibitory neurotransmitter of central nervous system is: \nSelect and explain. \nA. Aspartate, B. Gamma-aminobutyric acid, C. Glutamate, D. Acetylcholine', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. B. Gamma-aminobutyric acidGAMMA-AMINOBUTYRIC ACID is an inhibitory neurotransmitter found in brain and retina which is responsible for presynaptic inhibition.', 'role': 'assistant'}]