The Main Explanation for Why the Cheap Foreign Labor Argument

The main explanation for why the cheap foreign labor argument is a poor reason for restricting international trade is that:

A) workers who get paid less tend to have lower productivity than those who get paid more.
B) all firms and workers gain when there are no restrictions on international trade.
C) infant industries such as steel and automobiles need to be protected.
D) specialization and free trade usually raise the prices of all the traded goods, so that the workers can get paid more.