Torpedo Digital Company, a communications equipment manufacturer, recently fell victim to a fraud scheme developed by one of its employees. To understand the scheme, it is necessary to review Torpedo's procedures for the purchase of services. The purchasing agent is responsible for ordering services (such as repairs to a photocopy machine or office cleaning) after receiving a service requisition from an authorized manager. However, since no tangible goods are delivered, a receiving report is not prepared. When the Accounting Department receives an invoice billing Torpedo for a service call, the accounts payable clerk calls the manager who requested the service in order to verify that it was performed. The fraud scheme involves Ross Dunbar, the manager of plant and facilities. Ross arranged for his uncle's company, Capo Industrial Supplies and Service, to be placed on Torpedo's approved vendor list. Ross did not disclose the family relationship. On several occasions, Ross would submit a requisition for services to be provided by Capo Industrial Supplies and Service. However, the service requested was really not needed, and it was never performed. Capo Industrial Supplies and Service would bill Torpedo for the service and then split the cash payment with Ross. In the case of Torpedo, which of the following would be the best way to prevent this fraud? a. Have a person other than the manager requesting a service fill in the date and time the service was received and sign a service verification form. b. Have someone from Accounting call the vendor to see if the service had been performed. c. Make sure that Purchasing has a list of all approved vendors. d. Compare the invoice amount with the amount of the check for the service