The Fact That Money Serves as a Medium of Exchange

The fact that money serves as a medium of exchange as well as a unit of account is a potential cause of trouble because anything that alters the real value of the domestic money in terms of its purchasing power over goods and services

A) will also alter the real terms of those existing contracts that use money as the unit of account.
B) will also alter the real terms of those existing contracts that use money as the medium of exchange.
C) will invalidate existing contracts that use money as the unit of account.
D) will cause people to hoard money.