Which of the following would best contribute to the success of a guest auditor program...

The purpose of a guest auditor program is to leverage subject matter expertise from other areas while also enhancing collaboration and mutual learning between business units and internal audit. Allowing guest auditors to interact with internal audit staff fosters knowledge sharing, trust, and future cooperation.

Option A may create conflicts of interest. Option B compromises independence by allowing guest auditors to design and test audit procedures. Option C provides feedback but occurs after the engagement, not during.