If the chief audit executive (CAE) is uncertain that the current audit team has all the required knowledge to conduct the engagement, the most appropriate course of action is to use an external service provider. This helps preserve the independence and objectivity of the internal audit function.

Expertise: External service providers bring specialized knowledge and expertise that may not be available within the internal team.

Independence: Utilizing an external provider ensures that the audit maintains its independence and objectivity, avoiding any potential conflicts of interest.

Quality: Ensures that the audit engagement is conducted with the highest standards, leveraging the external provider ' s experience and skills.