Concept:A quota is a physical limit placed on the quantity of a good that can be imported.Explanation:The question asks for the trade control measure used when imports are restricted to a definite quantity.Excise duties and import duties are taxes, not quantity limits.A tariff is a tax on imported goods.A quota fixes the maximum amount of a product that may be imported.Therefore, limiting imports to a definite quantity is called a quota.Answer:C. quotas