Which of the following is the BEST way to detect potentially fraudulent purchases where an employee can approve a receipt of an item or service that the employee also procured?

A. Require staff training on entering purchase orders into the enterprise resource planning (ERP) system.
B. Require receipts to be entered against purchase orders by someone other than the buyer.
C. Requite that invoices can only be paid when matched with purchase orders.
D. Require purchase orders to originate from the same individual with designated authority.