Which of the following could cause a Denial of Service (DoS) against an authentication system?

Encryption of audit logs affects the confidentiality of log data but does not consume excessive storage or block authentication services from functioning, so it does not cause a DoS.

While failing to archive logs can eventually lead to storage exhaustion, the question asks what 'could cause' a DoS, and the act of not archiving is a contributing condition rather than the direct mechanism that a high-volume source like remote access logs represents.

Hashing of audit logs is an integrity-protection mechanism that adds minimal overhead and does not consume storage in a way that would deny access to the authentication system.

Remote access audit logs generate extremely high volumes of log data because every authentication attempt, session establishment, and access event is recorded. If the storage allocated for these logs becomes full and the system is configured to halt operations when it cannot write audit entries (a common security requirement), the authentication system itself can be rendered unavailable, constituting a DoS condition.