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
The drug used in the treatment of cessation of smoking  & tobacco addiction 
Select and explain. 
A. Vareniciline, B. Acamprosate, C. Baclofen, D. Naltrexone
A: Vareniciline
Answer: A: Vareniciline 
Explanation: Vareniciline is a partial agonist at α4 β2 subtype of Nicotine receptor used to treat tobbacco addiction.