Final answer:
The element that represents the hash of the previous block in a blockchain is the previous hash. It links the blocks together securely and is sensitive to any changes in the block's data.
Step-by-step explanation:
In a block in a blockchain, the element that represents the hash of the previous block is d) previous hash. Each block in a blockchain contains a unique code called a hash that distinguishes it from all other blocks. The previous hash serves as a reference in the blockchain's linking mechanism, ensuring that the blocks form an unbreakable chain in a specific sequence, which enhances security and prevents tampering with the block's data.
The hash is generated by a mathematical function that turns digital information into a string of numbers and letters; if that information is edited in any way, the hash code changes as well.