Which of the following is the most effective control procedure

Which of the following is the most effective control procedure to detect vouchers that were prepared for the payment of goods that were not received?

a. Count goods upon receipt in storeroom.
b. Match purchase order, receiving report, and vendor’s invoice for each voucher in accounts payable department.
c. Compare goods received with goods requisitioned in receiving department.
d. Verify vouchers for accuracy and approval in internal audit department.