What does the WTO's nondiscrimination policy mean? a. If country A lowers a trade barrier for country B, country B should do the same for country A. b. If country A lowers a trade barrier, it has to do the same for all WTO member countries. c. If country A lowers a trade barrier for country B, the U.S. should do the same for country B. d. If country A lowers a trade barrier for country B, all WTO member countries should do the same for country B