Which of the following best demonstrates the application of due professional care?

Demonstrating due professional care involves ensuring that the internal audit activity follows established guidelines and standards for conducting audit engagements. By establishing internal audit manuals, an audit lead provides a structured approach and standardized procedures for the internal audit activity, which helps in maintaining consistency, quality, and adherence to professional standards. This practice exemplifies the application of due professional care by promoting thorough and well-documented audit processes.

The IIA Standards: Standard 1220 – Due Professional Care: "Internal auditors must apply the care and skill expected of a reasonably prudent and competent internal auditor. Due professional care does not imply infallibility."

IIA Practice Guide: "Quality Assurance and Improvement Program": Highlights the importance of internal audit manuals and procedures in maintaining due professional care.