A

问题如下：

Cryptocurrencies are a common form of digital asset that

选项：

A.

can be mined only through “proof of work” on blockchain networks

B.

exist both in physical forms and electronic records with rights to use, buy, or sell by owners.

C.

can be used to transfer or store value, which allows time-efficient transactions between parties without the need for an intermediary.

解释：

The correct answer is C. Cryptocurrencies are used to transfer or store value, which allows near-real-time transactions between parties without the need for an intermediary. As electronic mediums of exchange, cryptocurrencies lack physical form and exist only as electronic records on distributed ledgers. Depending on the particular consensus protocols used, cryptocurrencies can be generated either by “proof of work” or “proof of stake” by miners or validators on networks.