Final answer:
An increase in the excise tax on cigarettes raises the price of cigarettes by shifting the supply curve for cigarettes leftward.
Step-by-step explanation:
An increase in the excise tax on cigarettes raises the price of cigarettes by shifting the supply curve for cigarettes leftward. When the tax on cigarettes increases, it raises the cost of production for cigarette manufacturers. As a result, they supply fewer cigarettes at each price level, leading to a leftward shift in the supply curve.