Which of the Following Is the Best Example of a Tariff

Which of the following is the best example of a tariff?

A) a subsidy from the government to domestic manufacturers of residential air conditioners to enable them to compete more effectively with foreign producers
B) a limit on the quantity of residential air conditioners that can be imported from a foreign country
C) a $150 fee imposed on all imported residential air conditioners
D) a tax placed on all residential air conditioners sold in the domestic market to help offset the impact of emissions on the environment