This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
Gamma-aminobutyrate is synthesized from? 
Select and explain. 
A. Fumarate, B. Glutamate, C. Histidine, D. Glycine
B: Glutamate
Answer: B: Glutamate 
Explanation: Gamma-aminobutyric acid (GABA) is formed by decarboxylation of L-glutamate.