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

Representative money is an item such as a token or piece of paper that has no intrinsic value but can be exchanged on demand for a commodity that does have intrinsic value, such as gold, silver, copper, and even tobacco. 
So the anwser is D

Um george washington i think !