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 for country B, all WTO member countries should do the same for country B.
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, it has to do the same for all WTO member countries.