Which of the following is not an instance in which the U.S. Trade Representative may take retaliatory action against a foreign country? a. The foreign country's policies violate the legal rights of the U.S. and restrict U.S. commerce. b. The foreign government permits forced labor. c. The foreign government's policies are unreasonable or discriminatory and burden or restrict U.S. trade or foreign investment. d. None of the above is discretionary, rather, retaliation by the U.S. Trade Representative is mandatory in all three instances.