Which of the following is FALSE concerning decentralized digital currency $($eg$.$Bitcoin$)?$a$)$ Lack of regulation makes them and their exchanges vulnerable to fraud and manipulation.b$)$ They have significant price volatility which makes them a poor "store of value".c$)$ They are unlikely to be able to handle to volume of transactions in today's global commerce.d$)$ They are completely protected by encryption technology and can never be stolen.