The correct answer is D) the power to tax.
Congress can use the power to tax to help protect American car makers from foreign competition.
If there are many types of cars coming from Japan, for instance, that are cheaper and are displacing the sales of American cars such as Ford, General Motors or Chrysler, the US Congress has the power to tax those imported cars to make the US cars more competitive. This way, the Japanese cars could have similar prices than American cars.
