Choice "D" is correct. In order to have an appropriate segregation of duties, the purchasing department should prepare the purchase order, the accounts payable department should match the purchase order, receiving report, and vendor invoice, and the treasurer should actually make the payment.
Choice "a" is incorrect. The accounts payable department (not the treasurer) matches the purchase order, receiving report, and vendor invoice before approving the voucher for payment.
Choice "c" is incorrect. The receiving department prepares a receiving report, but does not match it with the purchase order and the invoice. Matching these documents should be done by the accounts payable department. In addition, the treasurer, and not the accounts payable department, should make the payment.
Choice "b" is incorrect. The manager of the department requesting the goods is responsible for preparing a purchase requisition, not a purchase order. The purchasing department then prepares the purchase order. The accounts payable department should match the documents, but should not make the payment. Payment should be made by the treasurer.