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: Pharmacology
In depression, there is deficiency of : 
Select and explain. 
A. 5–HT, B. Acetylcholine, C. Dopamine, D. GABA
A: 5–HT
Answer: A: 5–HT 
Explanation: None