Which of the following is a common type of trade barrier?

An import quota is a common type of trade barrier that restricts the quantity of a particular good that can be imported into a country during a specific time period. By limiting the availability of foreign goods, import quotas aim to protect domestic industries from foreign competition and can help nurture local markets. This form of trade barrier directly impacts supply, potentially raising prices for consumers as the selection of imported products is diminished. Implementing import quotas can also lead to diplomatic tensions and retaliatory measures from trading partners who are affected by such restrictions.

The other options, while they relate to trade and economic activity, do not constitute traditional trade barriers. A consumer tax is generally a fiscal policy tool rather than a direct restriction on trade, and it applies universally to goods sold within a country. A distribution agreement typically refers to the arrangement between a supplier and distributor for the sale of goods, which does not inherently act as a barrier to trade. Sales incentives, aimed at encouraging purchases or boosting sales, influence market behavior but do not impede the free flow of goods across borders. These distinctions underscore why an import quota stands out as a clear example of a trade barrier.