An internal auditor is concerned that fraud, in the form of payments to fictitious vendors, may exist. Company purchasers, responsible for purchases of specific product lines, have been granted the authority to approve expenditures up to $10,000. Which of the following applications of generalized audit software would be most effective in addressing the auditor’s concern?
a. List all purchases over $10,000 to determine whether they were properly approved.

b. Take a random sample of all expenditures under $10,000 to determine whether they were properly approved.

c. List all major vendors by product line. Select a sample of major vendors and examine supporting documentation for goods or services received.

d. List all major vendors by product line. Select a sample of major vendors and send negative confirmations to validate that they actually provided goods or services.