The senior auditor's most appropriate course of action is to have the finding reinstated, because the auditee's claim of correcting the problem is not sufficient evidence to support the removal of the finding. The auditor should verify that the corrective action has been implemented effectively and that it has resolved the underlying issue or risk. The auditor should also document the evidence andresults of the verification in the work papers. The other options are not appropriate, because they either accept the auditee's claim without verification, delegate the responsibility to the auditee or escalate the issue unnecessarily. References:
ISACA, CISA Review Manual, 27th Edition, chapter 1, section 1.51
ISACA, IT Audit and Assurance Standards, Guidelines and Tools and Techniques for IS Audit and Assurance Professionals,section12062