The
core of all forms of money throughout the history of mankind is faith.
Suppose you sell a pack of cheese to somebody
and they give you a hundred rupee note. Why do you accept that worthless piece
of paper in exchange of the real commodity which you can actually consume. The
reason is faith,
you have faith that when you take that piece of
paper to somebody they will also accept it and give you something real that you
want.
If you feel that nobody will accept that paper
then you won't accept it either.
So what money does? It makes transactions easier. And help overcome
the limitations the barter system. Anything can be used as money if everybody
is willing to accept it in transaction. It should be generally acceptable to
people. It could be virtually anything from a piece of plastic, stamp, buttons
etc.
Given of course everybody believes in those
things and has confidence in them. In past even bars of clay has been used as
money in some civilizations.
So that's what money does. Anything that do this function is money. So money is what money does. Hence, correct answer is option A.