It Is Difficult to Test Whether the Velocity of Money

Multiple Choice

It is difficult to test whether the velocity of money is constant over time because

A) there has been very little variation in the money supply over time.
B) there may be a time lag between a change in the money supply and its effects on nominal GDP.
C) there is only one definition of the money supply.
D) it is difficult to measure the value of nominal GDP over time.