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: Psychiatry
Neurotransmitter mainly involved in OCD is : 
Select and explain. 
A. GABA, B. NE, C. Dopamine, D. Serotonin
D: Serotonin
Answer: D: Serotonin 
Explanation: Serotonergic system is implicated in the pathogenesis of OCD. Therefore selective serotonergic reuptake inhibitors is used to relieve OCD symptoms.