What is the biggest disadvantage of a barter system compared to a system that uses money?

a. All commodities are difficult to transport and therefore inefficient for exchange.

b. It is difficult to find goods to trade in a barter system that satisfy the needs of society.

c. Commodities are difficult to use as a store of value.

d. A standardised unit of account cannot exist in a barter system.

e. Each trade requires a double coincidence of wants.