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

A) a subsidy from the U.S. 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

Answer: B