For US Workers in Tradable Sectors Such as Manufacturing, the Effect

For U.S. workers in tradable sectors such as manufacturing, the effect of globalization has been:

A) to push wages up relative to those in nontradable sectors such as government or service workers.
B) to cause greater upward mobility for those workers while reducing downward mobility.
C) to push wages down or leave them unemployed.
D) to reduce unemployment in this group while leaving wage rates about the same.