Answer:
United States continue to have quotas because it increases the price of imported Sugar and thereby reducing the quantity demanded.
Step-by-step explanation:
To start with, quotas is a restriction imposed by a government. Quotas limits the quantity of a good that can be imported into a country during a specific period of time. In this question, an import license specifies the quantity of Sugar that be brought into (imported) the USA.
United States continue to have these quotas because import quotas reduces the supply of imported goods (Sugar), thereby, preventing an uncontrolled importation of Sugar. This raises the price of imported Sugar against the price of locally produced Sugar which is lower in price. Intuitively, consumers will go for lower price (locally produced Sugar) which satisfies the law of demand for normal goods.
Therefore, it helps the domestic producers to stay in the competition.