HELP ME WITH ECON!

Why has much clothing manufacturing moved from the United States to other countries?
Select one:

a. Nations with large, low-skilled workforces have a comparative advantage for assembly-line production.
b. Most of the market for textile products has shifted overseas.
c. American workers have a weaker work ethic today than in the past.
d. Education in this country has not kept up with the needs of the 21st century economy.