Why did coins replace other mediums of exchange? they had common value and were easy to steal. they were easy to make and difficult to use. they had high value and low weight. they had changing value and were hard to duplicate

They had changing value and were hard to duplicate.

The answer is They had changing quality and were difficult to copy  

Explanation:

A medium of trade is a delegate instrument used to encourage the deal, buy or exchange of products between gatherings. For an instrument to work as a medium of trade, it must speak to a standard of significant worth acknowledged by all gatherings. In current economies, the medium of trade is currency.Medium of Exchange: When cash is utilized to middle the trading of merchandise and enterprises, it is playing out a capacity as a medium of trade. Unit of Account: It is a standard numerical unit of estimation of market estimation of products, administrations, and different exchanges.