Which of the following is the most efficient audit procedure for the detection of unrecorded liabilities at the balance sheet date?

a. Obtain an attorney’s letter from the client’s attorney.
b. Confirm large accounts payable balances at the balance sheet date.
c. Examine purchase orders issued for several days prior to the close of the year.
d. Compare cash disbursements in the subsequent period with the accounts payable trial balance at year-end.