Which of the following is the best way for internal auditors to demonstrate their proficiency...

The best way for internal auditors to demonstrate their proficiency to effectively carry out their professional responsibilities is to obtain appropriate professional certifications or other designations. These credentials, such as Certified Internal Auditor (CIA) or Certified Information Systems Auditor (CISA), are recognized indicators of an auditor’s commitment to continuing education, professionalism, and adherence to industry standards.

IIA Standards for the Professional Practice of Internal Auditing and Continuing Professional Education requirements