Where is Tom most likely to find information on the approval process for modifications to system security settings?

The change log is the most appropriate source for Tom to find information on the approval process for modifications to system security settings. A change log records all changes made to the system, including approvals, who authorized the changes, the specifics of the modifications, and timestamps. This thorough documentation helps in understanding the accountability and governance aspects of system modifications, ensuring that security policies are being followed and that there is a traceable history of decisions made regarding security settings.

The other options, although they document important activities related to the system, serve different purposes. The system log typically records operational events and errors within the system, helping administrators troubleshoot issues rather than tracking security policy changes. The security log focuses on security-related events, such as unauthorized access attempts or modifications to security settings, but not necessarily the approval process behind those changes. The application log details specific applications' activities, which may include errors and operational status, but it does not specifically track the approval process for security modifications.

Therefore, the change log stands out as the dedicated resource for tracking and auditing the approval process for any modifications made to system security settings.