In which form of exchange are goods used as medium of exchange?

Correct — A. In barter, the goods themselves are the medium — grain is handed over for cloth, with no money standing between them.

The remaining three forms all move money in some shape: as cash, as a deferred money payment, or as a money transfer over a platform.

Goods serving as the medium is what makes it option (a).

Why the others are wrong

• (b)
  Currency exchange — Currency exchange puts money at the centre, usually trading one country's currency for another's. The medium there is money, not goods.
• (c)
  Credit exchange — Credit exchange shifts the timing of payment, not the medium. What is finally handed over is still money, only later.
• (d)
  Online exchange — Online exchange names the channel — a platform or an app. Payment made on it is still money, so it answers a different question.

Money exists because barter is clumsy. A barter deal needs a double coincidence of wants: you must want what I have while I want what you have, at the same moment and in tradeable proportions.

Barter also has no common measure of value, so every pair of goods needs its own exchange ratio, and perishable goods cannot carry value from one deal to the next.

Money answers all three problems by being generally accepted, divisible and durable, which is why textbooks describe it as a medium of exchange, a unit of account and a store of value.

Key facts

• Barter is the direct exchange of goods for goods, with no money as an intermediary.
• Barter requires a double coincidence of wants between the two parties.
• Money's textbook functions are medium of exchange, unit of account, store of value and standard of deferred payment.

Common traps

• Reading medium of exchange as the place where exchange happens, which pulls candidates to the online option.
• Treating credit as a separate medium when it only defers a payment still made in money.

No directly related past PYQ was found.