The correct answer is B) China.
The country that did the most to exploit loopholes in the North American Free Trade Agreement (NAFTA) was China.
Yes, China made everything on its hands to continue to take advantage of the agreement "loopholes" and kept its trading processes with the United States, México, and Canada.
Chinese exportations can be seen in practically every product in these three countries, especially, the United States.
NAFTA wanted to generate many positive factors for the three countries, Mexico, Canada, and the United States. But as always happen in free trade agreements, the reality shows many different ourcomes for the three of them. And Chine played a key role in these results.
During Trump's administration, the Congresses of the three countries analyzed the new free agreement after the revisión of NAFTA. The new agreement is called the “USMCA” or United States-Mexico-Canada Agreement and was signed on September 30, 2018, and was ratified by the Congress of the three countries in the firsts months of 2019.