Which of the following questions would most likely be included in an internal control questionnaire concerning the completeness of purchase transactions?

a. Is an authorized purchase order required before the receiving department can accept a shipment or the accounts payable department can record a voucher?

b. Are prenumbered purchase requisitions used and are they subsequently matched with vendor invoices?

c. Is there a regular reconciliation of the inventory records with the file of unpaid vouchers?

d. Are prenumbered purchase orders, receiving reports, and vouchers used, and are the entire sequences accounted for?