Which of the following is an example of a non-tariff barrier?

A non-tariff barrier refers to restrictions other than tariffs that countries use to control the amount of trade across their borders. Import quotas are a perfect example of this type of barrier, as they directly limit the quantity of a specific product that can be imported into a country. This restriction can protect domestic industries from foreign competition, ensuring that local businesses have a larger share of the market.

Sales taxes and export taxes relate to financial levies but do not directly restrict the volume of trade in the same manner as quotas. Customs duties, on the other hand, are tariffs themselves, which set a fixed fee on goods being imported and are thus considered tariff barriers. Through import quotas, countries can manage trade without imposing a direct monetary cost per transaction, showcasing the various forms of protectionist policies that go beyond tariffs.