The internal audit department is investigating a possible breach of security. One of the auditors is sent to interview the following employees:
Employee A Works in the accounts receivable office and is in charge of entering data into the finance system.
Employee B Works in the accounts payable office and is in charge of approving purchase orders.
Employee C Is the manager of the finance department, supervises Employee A and Employee B, and can perform the functions of both Employee A and Employee B.
Which of the following should the auditor suggest be done to avoid future security breaches?