Explanation

Option C is correct because this is a fundamental characteristic of distributed ledger technology (DLT). In DLT systems:

1. Consensus mechanisms (like Proof of Work, Proof of Stake, Practical Byzantine Fault Tolerance, etc.) are essential for maintaining the integrity and consistency of the ledger.
2. Nodes (participants in the network) must reach agreement on the validity of transactions and the current state of the ledger.
3. This agreement ensures that all copies of the ledger across the network remain synchronized and consistent.

Why the other options are incorrect:

Option A is incorrect because DLT is not necessarily energy-efficient. While some consensus mechanisms (like Proof of Stake) are designed to be more energy-efficient than others (like Proof of Work), DLT systems generally require significant computational resources for transaction verification and consensus. Bitcoin's Proof of Work mechanism, for example, is notoriously energy-intensive.

Option B is incorrect because one of the key features of DLT is immutability. Once a transaction is recorded on a distributed ledger, it cannot be easily deleted or altered. This immutability is achieved through cryptographic hashing and the distributed nature of the ledger, where each block contains a hash of the previous block, creating a chain that is extremely difficult to modify retroactively. If an error occurs, a new correcting transaction must be made, rather than deleting the incorrect record.