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

Money

The ancestor of the monetary system is of course the barter system. A farmer could trade his produce for the fish obtained by a fisherman or the cloth produced by a weaver. Even today the barter system tends to come back into style in places suffering from social breakdown, or as an informal sideline activity in more harmonious lands. However, trying to reach agreement over the relative value of different things tends to be time-consuming and vexing, and so societies tended to converge towards a common medium of exchange. Pacific islanders used shells; Aztecs used cacao beans, the main ingredient of chocolate. Livestock was common among herding cultures; slaves were sometimes used, too, but they were much harder to control than cattle and so not as popular; and many cultures used salt, including the Romans for a time- hence, the modern term "salary". Incidentally, after World War II cigarettes were used as a medium of exchange in many countries then in very poor condition, and it is said that in Italy “penny candy” was commonly used as “small change” even into the 1970s.

The medium that gradually gained widespread acceptance was precious metals such as gold and silver. Coins are said to have been invented by the Lydians, a people of Asia Minor, sometime after 640 BC. They used stamped ingots of "electrum", a naturally occurring amalgam of silver and gold. The scheme was refined by King Croesus, ruler of Lydia from 560 to 546 BCE, who introduced coins of true gold. He is still identified with wealth in the expression "rich as Croesus". The introduction of coinage was a great boon for traders, simplifying transactions and allowing them to be conducted more smoothly over long distances.

[1] Coinage also helped support far-flung empires; the Roman Empire was built on silver and gold coins, as well as military victories. As the empire expanded, the expenditures of the state led to the debasement of the coins, beginning with an act of the Emperor Nero in 64 A.D. By the end of his reign, the silver content of Roman coins had shrunk by 10%. [2] Other emperors followed his example, and over 200 years from the start of the process, the content shrank to 5%. The coins’ buying power fell accordingly.

[3] Coins are still with us, though they are now little more than tokens made of non-precious metals. [4] Few countries still use silver or gold coins as anything other than collector's items.

Which of the following best expresses the essential information in the hightlighted sentence in the passage? Even today the barter system tends to come back into style in places suffering from social breakdown, or as an informal sideline activity in more harmonious lands.

Graduate students often spend their weekends_______data for their research.