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: Physiology
Glutamate as a neurotransmitter is synthesized mainly in which part of basal ganglia 
Select and explain. 
A. Globus pallidus interna, B. Globus pallidus externa, C. Subthalamic nucleus, D. Putamen
C: Subthalamic nucleus
Answer: C: Subthalamic nucleus 
Explanation: Connections in Basal ganglia

Substantia nigra pars compacta (SNPC) to Striatum (Caudate nucleus & Putamen)- Dopaminergic 
Striatum to Substantia nigra pars reticulata (SNPR)- GABA 
Striatum to Globus pallidus inner segment & external segment- GABA​
Globus pallidus external segment to subthalamic nucleus and internal segment- GABA​
Subthalamic nucleus to Globus pallidus external segment and internal segment.- Glutamate​
Within the striatum- Cholinergic interneurons.