Final answer:
The supply curve for a commodity typically shifts upward when an excise tax is imposed. Therefore, the correct answer is B) The supply curve shifts upward.
Step-by-step explanation:
The supply curve for a commodity typically shifts upward when an excise tax is imposed. When a tax is introduced, it raises the costs of production for sellers, leading to a decrease in supply.
For example, let's consider a supply curve for gasoline. When an excise tax is imposed on gasoline, it increases the production costs for gasoline producers. As a result, they supply fewer units of gasoline at each price level, causing the supply curve to shift upward.
Therefore, the correct answer is B) The supply curve shifts upward.