Which of the following actions taken during an audit engagement is the best demonstration of...

Considering the possibility of noncompliance or irregularities at all times during an engagement best demonstrates an internal auditor's due professional care. This proactive approach to skepticism ensures that the auditor remains vigilant and prepared to identify any indications of noncompliance or irregular activities, which is central to upholding the integrity of the audit process.

IIA standards on due professional care, which emphasize the importance of maintaining an attitude of professional skepticism throughout the audit process.