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
The byproduct of GABA is 
Select and explain. 
A. Glutamate, B. Aspaate, C. Glycine, D. Succinate
D: Succinate
Answer: D: Succinate 
Explanation: It is clear from this picture that GABA metabolite is succinate.