How Has the North American Free Trade Agreement (NAFTA)affected U

How has the North American Free Trade Agreement (NAFTA) affected U.S.unions?

A) Because of the higher demand for Mexican labor, Mexican unions have been able to increase wages enough that U.S. firms no longer have a cost advantage in moving unionized jobs to Mexico.
B) Unionized Canadian manufacturers have moved operations to non-union plants in the U.S.
C) Unionized U.S. firms have moved their operations to Mexico, thus reducing union employment in the U.S.
D) The lowering of tariffs and trade restrictions has allowed unionized U.S. firms to sell more of their products to Canada and Mexico, thus increasing employment for union members.