单项选择题

Task 8
Primitive man learned that he could have more of the good thing of life by trading with other men. For example, he could exchange an extra animal skin for food, a club, or a spear. With the coming of civilization man began to use grain, olive oil, crops, and cattle as barter items. But trading with goods was inexact and burdensome. It was necessary to carry around a load of hay on your back to exchange for a dozen bushels of wheat. In about 700 B.C., a people in Asia Minor known as the Lydians decided that gold, silver, and other metals should stand for the value of goods. They invented a rough coin called the stater, which was made of gold and silver. A certain number of staters could be used to buy a bag of salt, a tool, or clothing. In this way the old custom of barter was gradually replaced by the use of money, although some primitive people still use goods as a medium of exchange.
It is definite from the passage that trading with goods______