Which of the Following Would Probably Be the Least Effective

Multiple Choice

Which of the following would probably be the least effective control to mitigate the risk of paying an invoice payable to a phony vendor for inventory purchases,mailed to the company by an employee attempting to commit fraud?

A) Only pay from original invoices.
B) Cancel all invoices and supporting documentation when paid.
C) Strict access and authorization controls for the approved vendor master file.
D) Require three-way match for all inventory purchase invoices.