Deferring remediation testing until the next audit is justified only when there are significant changes in the audit environment that affect the relevance or validity of the audit observations and recommendations. For example, if there are changes in the business processes, systems, regulations, or risks that require a new audit scope or approach. The other options are not valid justifications for deferring remediation testing, as they do not address the timeliness or quality of the audit follow-up process. The auditor who conducted the audit and agreed with the timeline has left the organization does not affect the responsibility of the audit function to ensure that remediation testing is performed as planned. Management’s planned actions are sufficient given the relative importance of the observations does not guarantee that management will actually implement those actions or that they will be effective in addressing the audit issues. Auditee management has accepted all observations reported by the auditor does not eliminate the need for verification of remediation actions by an independent party. References: CISA Review Manual (Digital Version), Chapter 2, Section 2.4