Which of the Following Defines the "Medium of Exchange" Function

Which of the following defines the "medium of exchange" function of money?

A) To provide a common measurement of the relative value of different goods and services.
B) The ability of money to hold value over time.
C) The materials used manufacture money are of medium grade so that people will not hoard money for its commodity value.
D) Money that is widely accepted in exchange for goods and services.