I'm studying for my CPA exam. Can anyone help me with this one?

An auditor suspects that certainclient employee are ordering merchandise for themselves over the internetwithout recording the purchase or receipt of the merchandise. When vendor's' invoices arrive one employee approves the invoice for payment. After the invoices are paid, the employee destroys the invoices and related vouchers. In gathering evidenceregarding the fraud, the auditor most likely would select items for testing from a file of all:

Cash disbursements

Approved vouchers

Receiving reports

Vendors' invoices