Allows goods and services flow more freely across the borders of the us, canada, and mexico.

NAFTA

NAFTA stands for North American Free trade agreement allows the United States, Canada, and Mexico. It went effective on Jan, 1994.The purpose of NAFTA was to eliminate the tariffs on trade and investment among these three countries.It also regulates supranational administrative authorities with the full power to eliminate disputes based on regular conflicts, tariffs, and environmental laws.

On September 30, 2018, all three countries had a table talk and renegotiated the North American Free trade agreement now it is called Untied States-Mexico-Canada agreement. Each country will ratify it according to its legislature. This process will take some time, it couldn't be effective before 2020.

d. the polar jet stream   lies between the polar easterlies and trade winds should be your answer