Which is an example of a quota _____ .

A quota is a specific limit placed on the quantity of a particular good that can be imported or exported during a given timeframe. In the context of international trade, quotas are used by governments to regulate the amount of trade in certain goods, thereby managing domestic market supply, protecting local industries, or attempting to balance trade deficits.

The choice highlighting the limitations on the number of computers brought into the country clearly exemplifies a quota, as it denotes a restriction on how many units of that product can enter the market. This illustrates the concept of enforcing specific boundaries on imports to influence economic factors like domestic production and consumer choice.

The other options do not represent quotas. Limiting the overall number of cars sold (the first choice) does not specifically pertain to imports; it could refer to domestic sales without an import restriction. Tariffs (the third choice) are taxes imposed on imported goods but do not limit the quantity of those goods. Lastly, the imposition of a tax on sugar (the fourth choice) doesn't establish a quantity restriction; rather, it affects the cost of sugar without limiting how much can be imported.