Final answer:
The supply curve for cigarettes will shift to the left by exactly $1.25 when a tax of $1.25 per pack of cigarettes is placed on the sellers.
Step-by-step explanation:
The correct answer is d. to the left by exactly $1.25.
When a tax is placed on the sellers of cigarettes, the supply curve shifts to the left by the amount of the tax. In this case, the tax is $1.25 per pack of cigarettes, so the supply curve will shift to the left by exactly $1.25.
This means that the sellers of cigarettes will now have to sell their cigarettes at a higher price to cover the cost of the tax, which will lead to a decrease in the quantity of cigarettes supplied.