Which of the following technologies is employed to ensure the data transmitted in blockchain is secure?

The use of cryptography is fundamental to the security and integrity of data in blockchain technology. Cryptography provides processes such as hashing and encryption that protect data as it is being stored and transmitted. In blockchain, each block of data is linked to the previous block through a cryptographic hash, creating a secure and immutable chain. This means that altering any piece of information would require altering all subsequent blocks, which is computationally impractical and effectively prevents tampering.

In addition to maintaining the integrity of data, encryption secures the data from unauthorized access or surveillance, thereby ensuring that only those with the appropriate cryptographic keys can read or interact with the data. This dual role of maintaining integrity and confidentiality is what makes cryptography an essential technology for blockchain security.

Other options, while they may play roles in the broader context of data management and access, do not provide the same level of security assurance that cryptography does. For example, transparent data sharing refers to making data available but does not secure the data. Centralized oversight contradicts the decentralized essence of blockchain, and public access to all transactions can enhance transparency but does not inherently protect against data breaches or unauthorized changes.