When trade barriers began to fall, what was the motivation for much of the foreign direct investment by non-U. S. firms

The motivations were all the advantages that the U.S. market offers.

These advantages are many, because the U.S. is a developed country, with a very large population, and a robust legal system that protects private property, including the property of non U.S. firms that invest in the country.

For these reasons, once trade barriers began to fall, many non U.S. firms took advantage of the new opportunities, and started to invest in the U.S. market.

c, theres a double tax on the business earnings

answer; ( prices are sticky);