All of the Following Are Reasons Countries May Be Unable

All of the following are reasons countries may be unable to use discriminatory trade practices to enforce labor standards EXCEPT

A) in order to be effective a coalition of countries must join together to impose them.
B) countries can never impose trade barriers on other sovereign nations.
C) the WTO requires nations to treat other nations the same.
D) a single country may be unsuccessful in convincing members of its trading block to participate in imposing the sanctions.
E) retaliation or a full blown trade war might result.