Answer:
B. They take away barriers to trading with other nations.
Step-by-step explanation:
Without free-trade agreements, Countries usually create a "Barrier" that can increase the cost of international trades. The are several types of trade barriers, but the most common example of this would be trade imports. Trade imports require foreign sellers to pay a sum amount of money before they can sell their product into our country.
With free-trade agreements, the governments of all the countries involved agree to eliminate this barrier. This made selling goods to another country that are part of the free-trade agreements become much cheaper and more efficient.