Smoking cessation drugs

Ans A) clonidine

NRT ,  varenicline (Chantix), and bupropion (Zyban) are the three principal firstline pharmacotherapies recommended for use either alone or in combination 

Clonidine and nortriptyline—as second-line pharmacotherapies for tobacco dependence typically used when a smoker cannot use first-line medications due to either contraindications or lack of effectiveness.

Ref Devita