Read the following passage and blacken the letter A, B, C, or D on your answer sheet to indicate the correct answer to the following questions.

In the American colonies there was little money. England did not supply the colonies with coins and did not allow the colonies to make their own coins, except for the Massachusetts Bay Colony, which received permission for a short period in 1652 to make several kinds of silver coins. England wanted to keep money out of America as a means of controlling trade: America was forced to trade only with England if it did not have the money to buy products from other countries. The result during this pre-revolutionary period was that the colonists used various goods in place of money: beaver pelts, Indian wampum, and tobacco leaves were all commonly used substitutes for money. The colonists also made use of any foreign coins they could obtain. Dutch, Spanish, French, and English coins were all in use in the American colonies.

During the Revolutionary War, funds were needed to finance the world, so each of the individual states and the Continental Congress issued paper money. So much of this paper money was printed that by the end of the war, almost no one would accept it. As a result, trade in goods and the use of foreign coins still flourished during this period.

By the time the Revolutionary War had been won by the American colonists, the monetary system was in a state of total disarray. To remedy this situation, the new Constitution of the United States, approved in 1789, allowed Congress to issue money. The individual States could no longer have their own money supply. A few years later, the Coinage Act of 1792 made the dollar the official currency of the United States and put the country on a bimetallic standard. In this bimetallic system, both gold and silver were legal money, and the rate of exchange of silver to gold was fixed by the government at sixteen to one.

Question: The expression “a means of'’ in paragraph 1 could be best replaced by.

_______was caused by breathing impure air over was once a common belief.