Adouble coincidence of wants
- is required when there is no item in an economy that is widely accepted in exchange for goods and services.
- is required in an economy that relies on barter.
- is a hindrance to the allocation of resources when it is required for trade.
- all of the above are correct.

All of the above are correct.

Explanation:

A double coincidence of wants is a situation in which two parties possess items that the other wants, so they can exchange items directly without using money.

It is required in a barter economy or an economy that does not use money or a fixed medium of exchange. Such an economy exchange is good for goods.  

Double coincidence of wants has a number of limitations. It reduces the scope for the specialization of goods. It creates problems inefficient allocation of resources. It also more time consuming to find someone who possesses what you need and wants what you have.

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