Public Blockchains Can Alter the Blockchain Ledger By

Multiple Choice

Public blockchains can alter the blockchain ledger by:

A) Creating a hard fork of the blockchain data, tooling and/or software
B) Achieving community consensus via a Smart Contract to update the ledger
C) Re-hashing the blocks from the total block height down to the genesis block
D) Blockchain ledgers are immutable and can never be altered