Exports from and Imports to the U

Exports from and imports to the U.S.were important to growth in the U.S.between 1790 and 1860 because

A) exports to other countries expanded the market base for U.S. manufacturing goods.
B) they supported the U.S. economy during a time in which it used more agricultural goods ?and crude materials than it produced.
C) they helped the U.S. and its trading partners gain wealth through international trade of those goods and services in which each produced at a comparative advantage.
D) they contributed to all of the above.