Number of times a unit of money changes hands in the course of a year is called

The correct answer is C. Velocity of money.

The velocity of money is a measure of the number of times a unit of money is spent in a given period of time. It is calculated by dividing the nominal GDP by the money supply. The velocity of money is important because it affects the inflation rate. A higher velocity of money means that money is being spent more quickly, which can lead to inflation. A lower velocity of money means that money is being spent more slowly, which can lead to deflation.

The other options are incorrect.

• Option A, supply of money, is the total amount of money in circulation in an economy. It is measured by the M1 and M2 monetary aggregates.
• Option B, purchasing power of money, is the amount of goods and services that can be purchased with a unit of money. It is inversely related to the price level.
• Option D, value of money, is the purchasing power of money. It is also called the real value of money.