Final answer:
Import quotas are used to control trade by imposing numerical limitations on the quantity of products that can be imported. In this case, a stock limit of 100 quintals is imposed for retail traders and 500 quintals for wholesale trade.
Step-by-step explanation:
Imposed
One way to control trade is through the imposition of import quotas, which are numerical limitations on the quantity of products that a country can import. These quotas can be set for different types of trade, such as retail and wholesale. In this case, a stock limit of 100 quintals is imposed for retail traders and 500 quintals for wholesale trade.