Restricting program functionality according to user security profiles is the best control for ensuring appropriate segregation of duties within an accounts payable department. An IS auditor should verify that the access rights and permissions of the accounts payable staff are based on their roles and responsibilities, and that they are not able to perform incompatible or conflicting functions such as creating, approving, or paying invoices. This will help to prevent fraud, errors, or abuse of authority within the accounts payable process. The other options are less effective controls for ensuring segregation of duties, as they may involve audit trails, access restrictions, or user identification. References:
* CISA Review Manual (Digital Version), Chapter 6, Section 6.31
* CISA Review Questions, Answers & Explanations Database, Question ID 223