Objects that hold no value by themselves but can be exchanged for something valuable are called currency.
a. phoney
b. substitute
c. commodity
d. representative

Objects that hold no value by themselves but can be exchanged for something valuable are called c) commodity currency. A commodity currency is defined as "a name given to currencies of countries who depend heavily on the export of certain raw materials for income.These currencies exist both in developing and developed countries.

Ithink the answer is c