Cryptocurrencies are digital tokens that are created independently of government money, and can act as a medium of exchange and store of value. Which other instrument could most reasonably fulfill the same function

Gold

Explanation:

From the question, we are informed about Cryptocurrencies which are digital tokens that are created independently of government money, and can act as a medium of exchange and store of value. One of other instrument that could most reasonably fulfill the same function is Gold. A medium of exchange can be regarded as a intermediary instrument which is a function of money that facilitate trade or purchase and selling between seller and buyers, and it must be accepted as payment for transactions. Such intermediary instrument as a medium of exchange are Gold, salt as well as stone. Gold was chosen by most of the commodity-money advocates as a medium of exchange as a result of the intrinsic property it posses, and it's fixed stock value