9. What follow-up procedure, if any, should the auditor perform when no response has been received for negative confirmation request?

a. Inspect underlying documents, such as sales invoice, shipping documents, and customers purchase order to evaluate the apparent validity of balances involved

b. Review the cash receipts journal to see if payments were received after year end

c. Inquire of management about the likely reason for the non-response

d. second request asking for a response

e. no follow-up procedure is necessary