A purchasing agent acquired items for personal use with the organization's funds. The organization allowed designated employees to purchase a specified amount per day in merchandise under open-ended contracts. Supervisory approval of the purchases was required, but that information was not communicated to the vendor. Instead of reviewing and authorizing each purchase order, supervisors foutinely signed the authorization sheet at the end of the month without reviewing any of the supporting documentation. Because purchases of this nature were not subject to normal receiving policies, the dishonest employee picked up the supplies at the vendor's warehouse. All purchases were for items routinely ordered by the organization. During the past year, the employee amassed enough merchandise to start a printing and photography business. Which of the following engagement procedures, performed by the internal auditor, is most likely to detect this fraud? A. Performing a trend analysis of printing supplies expenses for a 2-year period. B. Tracing prices and quantities on selected vendors' invoices to the related purchase orders. C. Recomputing the clerical accuracy of selected vendors' invoices, including discounts and sales taxes. D. Tracing selected canceled checks to the cash payments joumal and to the related vendors' invoices