Assume you are considering an entity's internal controls over credit sales and cash collection. System documentation was accomplished through a questionnaire and written narratives and, in conjunction with a transaction walk-through, revealed the following potential weaknesses in internal control, some of which, depending on their severity, could prompt you to set control risk at the maximum:

a. New customers are not approved before ordered goods are shipped.

b. Sales prices vary from customer to customer

c. No approval is required for returned goods from customers.

d. Subsidiary accounts receivable records do not always agree with the general ledger control account.

e. Blank checks are left unprotected in an unlocked safe.

Required: 

For each potential weakness, indicate a control or controls that management could implement to reduce the likelihood of errors or frauds.