Assume you are considering a client's controls over purchases and cash disbursements. System documentation was accomplished through flowcharts and narratives and, in conjunction with a transaction walk-through, revealed the following potential deficiencies:

a. Carrying costs of inventory have increased significantly since the prior year.

b. Prices for purchases are sometimes unusually high or fluctuate significantly from month to month.

c. Purchase discounts are not taken frequently.

d. During lunch, the controller commented to you that on two occasions during the year duplicate payments had been made for a single transaction.

e. Cash disbursements records do not always reconcile with general ledger control accounts.

Required: 

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