Solution and Explanation:
It has been assumed that law enforcement agency decided to address the negative externailities by levying or imposing the tax on the gasoline to be paid the gasoline seller.
A) The supply curve will shift leftward.
The supply curve and the demand curve must be kept in mind and the tax, price level, the quantity of goods that have a demand and the corresponding supply of level.
B) The new equilibrium will achieve the corresponding to the lower quantity level.