A fraud auditor confirms a representative number of open accounts receivable as of December 31 and investigates respondents' exceptions and comments. By this procedure the fraud auditor would be most likely to learn of which of the following?
a. One of the cashiers has been covering a personal embezzlement by lapping.
b. One of the sales clerks has not been preparing charge slips for credit sales to family and friends.
c. One of the computer control clerks has been removing all sales invoices applicable to his account from the data file.
d. The credit manager has misappropriated remittances from customers whose accounts have been written off.
e. None of the above.