The best answer is B. Implementing cryptographic hash functions.

To ensure integrity, the organization needs a control that can detect unauthorized alteration. Cryptographic hash functions are specifically designed to verify that data has not been modified. Timestamping helps with sequencing and timing, limiting access helps reduce risk of tampering, and archiving helps retention, but hashing is the strongest direct method for validating integrity. This answer is standard ISACA-aligned control reasoning based on the security objective of integrity.

ISACA’s log-management guidance emphasizes the need for trustworthy, purposeful logging and monitoring. For log data to be trusted as evidence or for operations, it must be protected against undetected modification. Among the given choices, cryptographic hashing is the most effective direct mechanism for that purpose.

References (Official ISACA):

ISACA Journal, Log Management as an Enabler for Data Protection and Automated Threat Detection.

ISACA Journal, A Framework for SIEM Implementation.