The cashier of Rock Company covered a shortage in the cash working fund with cash obtained on December 31 from a local bank by cashing, but not recording, a check drawn on the company's out-of-town bank. How would the auditor discover this manipulation?

a. Confirming all December 31 bank balances.

b. Counting the cash working fund at the close of business on December 31.

c. Investigating items returned with the bank cutoff statements.

d. Preparing independent bank reconciliations as of December 31.