Operating System (OS) baselines are of greatest assistance to auditors when reviewing system configurations. OS baselines are standard or reference configurations that define the desired and secure state of an OS, including the settings, parameters, patches, and updates. OS baselines can provide several benefits, such as:

Improving the security and compliance of the OS by applying the best practices and recommendations from the vendors, authorities, or frameworks

Enhancing the performance and efficiency of the OS by optimizing the resources and functions

Increasing the consistency and uniformity of the OS by reducing the variations and deviations

Facilitating the monitoring and auditing of the OS by providing a baseline for comparison and measurement

OS baselines are of greatest assistance to auditors when reviewing system configurations, because they can enable the auditors to evaluate and verify the current and actual state of the OS against the desired and secure state of the OS. OS baselines can also help the auditors to identify and report any gaps, issues, or risks in the OS configurations, and to recommend or implement any corrective or preventive actions.

The other options are not of greatest assistance to auditors when reviewing system configurations, but rather of assistance for other purposes or aspects. Change management processes are processes that ensure that any changes to the system configurations are planned, approved, implemented, and documented in a controlled and consistent manner. Change management processes can improve the security and reliability of the system configurations by preventing or reducing the errors, conflicts, or disruptions that might occur due to the changes. However, change management processes are not of greatest assistance to auditors when reviewing system configurations, because they do not define the desired and secure state of the system configurations, but rather the procedures and controls for managing the changes. User administration procedures are procedures that define the roles, responsibilities, and activities for creating, modifying, deleting, and managing the user accounts and access rights. User administration procedures can enhance the security and accountability of the user accounts and access rights by enforcing the principles of least privilege, separation of duties, and need to know. However, user administration procedures are not of greatest assistance to auditors when reviewing system configurations, because they do not define the desired and secure state of the system configurations, but rather the rules and tasks for administering the users. System backup documentation is documentation that records the information and details about the system backup processes, such as the backup frequency, type, location, retention, and recovery. System backup documentation can increase the availability and resilience of the system by ensuring that the system data and configurations can be restored in case of a loss or damage. However, system backup documentation is not of greatest assistance to auditors when reviewing system configurations, because it does not define the desired and secure state of the system configurations, but rather the backup and recovery of the system configurations.