This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Excitation and Action Potiential, Subject name: Physiology
_______________ is the major excitatory neurotransmitter in the brain. 
Select and explain. 
A. Ach, B. Aspaate, C. GABA, D. Glutamate
D: Glutamate
Answer: D: Glutamate 
Explanation: Glutamate is the major excitatory neurotransmitter; 60% of brain synapses are glutamatergic. GABA is the major inhibitory neurotransmitter and can be localized by using glutamic acid decarboxylase as a marker. A delta fibers which carry sharp pricking pain also release Glutamate.