Which feature of blockchain ensures that records cannot be altered retroactively?
- Decentralization
- Immutability
- Transparency
- Anonymity
Answer: Immutability
Immutability: once data is added to a block and chained via hashes, altering it requires recalculating all subsequent blocks across the network—computationally infeasible. Core to trustless systems. [[NITI Aayog Reports]]