The U.S. Social Security tax is an example of a

Money's function as a medium of exchange means that

A) money is a common denominator for expressing the prices of goods and services. B) money can be used to store wealth. C) money serves as an acceptable means of payment. D) money requires a double coincidence of wants.

A proportional income tax is defined as a tax for which

A) total taxes paid increase with the level of income. B) total taxes paid are independent of the level of income. C) the average tax rate increases with the level of income. D) the average tax rate is the same at all levels of income.