Following are ten internal control failures related to the revenues and cash collection processes.

a. Pre-formatted data entry screens
b. Pre-numbered documents
c. Programmed edit checks
d. 100% check for matching of customer orders and sales orders
e. 100% check for matching of sales orders, pick list, and packing slips
f. 100% check for matching of sales orders and invoices
g. 100% check for matching of deposit slip and customer check.
h. Prompt data entry immediately upon receipt of customer order
i. Customer verification
j. Independent authorization for shipments
k. Independent authorization for billing
l. Reasonableness check
m. Hash totals
n. Data back-up procedures
o. Program change controls
p. Sequence verification
q. Periodic confirmation of customer account balances

a customer ordered 12 boxes of your product (total of 144 items) for express shipment. Your data entry clerk inadvertently entered 12 individual items.
you enter sales and accounts receivable data in batches at the end of each week. Several problems have resulted recently as a result of recording invoices to the wrong customer account.
in an effort to boost sales, you obtain some of the stock of unissued shipping reports and create a dozen fictitious shipments. You submit these documents to the billing department for invoicing.
Checks are received by the mailroom and then forwarded to the accounts receivable department for recording. The accounts receivable clerk holds the checks until the proper customer account has been identified and reconciled.
several shipping reports have been misplaced en route to the billing department from the shipping department.
several sales transactions were not invoiced within the same month as the related shipment.
a sales clerk entered a non existent date in the computer system. The system rejected the data and the sales were not recorded.
upon entering sales orders in your new computer system, a sales clerk mistakenly omitted customer numbers from the entries.
a computer programmer altered the electronic credit authorization function for a customer company owned by the programmer cousin.
Customer orders were lost in the mail en route from the sales office to the accounting department (located at the company headquarters).

Required:
Select one internal control from the following list that would be most effective in the prevention of the failure. Indicate the letter of the control next to each failure above. Letters should not be used more than once and some letters may not be used at all.