What is the most effective method for an IS auditor to determine compliance with change control procedures?

Selecting the choice focused on identifying changes that have occurred and verifying approvals is effective because it directly addresses the core requirement for compliance with change control procedures. In order to assess whether an organization adheres to its change control processes, it is essential to look at what specific changes were made to the systems or applications and confirm that these changes were properly authorized.

This method allows the auditor to not only confirm that the changes were conducted but also to assess whether the appropriate approvals were obtained beforehand, reflecting adherence to established policies and procedures. By focusing on actual changes and their corresponding approvals, an auditor gains visibility into the operational effectiveness of the change control process.

Other choices may provide useful information, such as reviewing documentation or verifying access controls, but they do not as effectively demonstrate compliance with the specific procedures related to changes that occurred. For example, simply reviewing migration records or change control documentation without linking them to the actual changes made would not provide definitive proof of compliance or the effectiveness of the change management process.