Which of the following statements about Bitcoin miners is CORRECT: A. To be a Bitcoin miner, you don't have to join the Bitcoin network. B. In the Bitcoin network, there is a blockchain where each...

Which of the following statements aboutBitcoin miners is CORRECT:

A. To be a Bitcoin miner, you don't have to join the Bitcoin network.

B. In the Bitcoin network, there is a blockchain where each block header points to theNEXTblock header in the chain.

C. In the blockchain, within each block there’s a Merkle tree of all of the transactions included in that block.

D. The mining difficulty in the Bitcoin network is never changed.