A digital signature is a cryptographic technique that uses the sender's private key to generate a unique code for a message or document. The receiver can use the sender's public key to verify the authenticity and integrity of the message or document. A digital signature can prevent unauthorized change, as any modification to the message or document will invalidate the signature and alert the receiver of tampering.
References
What is a digital signature?
Digital Signature - an overview | ScienceDirect Topics
ISACA CISA Review Manual, 27th Edition, page 253

Automated monitoring tools increase the likelihood of detecting suspicious activity (Option A) by continuously analyzing security logs for anomalies.
ISACA CISA Reference: Security Information and Event Management (SIEM) solutions are recommended for privileged access monitoring.