Which of the following is the best audit procedure for determining the existence of unrecorded liabilities?
a. Examine confirmation requests returned by creditors whose accounts appear on a subsidiary trial balance of accounts payable.
b. Examine a sample of cash disbursements in the period subsequent to year-end.
c. Examine a sample of invoices a few days prior to and subsequent to the year-end to ascertain whether they have been properly recorded.
d. Examine unusual relationships between monthly accounts payable and recorded purchases.