Final answer:
The trade policy tool that mandates importers to apply for an exchange permit to buy foreign goods is Import licensing, a type of non-tariff barrier designed to control imports and protect domestic industries.
Step-by-step explanation:
The trade policy tool that requires importers to apply for an exchange permit in order to buy a foreign good is Import licensing. This is a type of non-tariff barrier used to control the volume of traded goods. An import license is a document issued by a national government authorizing the importation of certain goods into its territory. Governments may issue such licenses as part of their policy to manage the amount of foreign goods entering the country and to protect domestic industries from overseas competition.
Import quotas, on the other hand, are numerical limitations on the quantity of products that can be imported. These quotas can limit the supply of foreign goods, raise prices, and protect domestic industries from competition, as historically seen with the Reagan Administration's quota on Japanese automobiles or the Multifiber Agreement which managed textile imports and domestic production. While both import licensing and import quotas are protectionist measures, it is specifically the import licensing that mandates the application for an exchange permit.