Which of the following foundational elements ensures the integrity of a blockchain by cryptographically linking blocks?

The foundational element that ensures the integrity of a blockchain through the cryptographic linking of blocks is hashing. Each block in a blockchain contains a unique hash that is generated based on its contents and the hash of the previous block. This cryptographic hash function ensures that even a small change in the data of a block will result in a significantly different hash. Consequently, if someone attempts to alter the information in a block, it would be evident because the hash would no longer match, thus signaling tampering.

This chaining of blocks through hashes forms a secure and tamper-evident structure, making it extremely difficult for attackers to alter any block without being detected. The integrity of the entire blockchain depends on the accuracy of these hashes, as they create a verifiable trail from one block to the next. Hashing is therefore a crucial technique for maintaining the security and trustworthiness of the blockchain, ensuring that the data remains unchanged and authentic over time.