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
Stimulation of which of the following nerve causes an elevation in the mood - 
Select and explain. 
A. Olfactory N, B. Optic N, C. Trigeminal N, D. Vagus N
D: Vagus N
Answer: D: Vagus N 
Explanation: Left vagus nerve stimulation is used to elevate the mood in patients with treatment-resistant depression.