Comprehensive and Detailed Step-by-Step Explanation:

Reference to the IIA Code of Ethics - Confidentiality:

The principle of confidentiality requires internal auditors to respect and protect the value of information obtained during the course of their work and to avoid using it for personal gain.

Reasoning:

Option A is correct because refusing to use audit information for personal financial gain directly aligns with the principle of confidentiality.

Option B relates to competency and professional judgment, not confidentiality.

Option C pertains to avoiding conflicts of interest, which is an example of the principle of objectivity.

Application of Confidentiality:

Internal auditors must safeguard sensitive information and use it solely for legitimate audit purposes.