Answer:
C. because it does not produce enough oil.
Step-by-step explanation:
Although, the United States is one of the leading producers of oil, yet still import oil because it does not produce enough oil to meet the demand of its citizens. In other words, the United States consumes more than what she can produce.
Another reason is that most refineries in the United State are created basically for heavy crude whereas most of what she produce are light crude oil. The United States import the oil she is able to process while she export to other countries to complete the setup process.
The remedy to the above situation is when new refineries are built which are somewhat expensive or the existing refineries are upgraded to meet with the demand.