You are the auditor of John Benson Ltd., a manufacturer of a variety of paper and cardboard stationery products. Product lines range from everyday items that are low value but high volume to more expensive and specialized items that are produced for niche markets. Closing inventory includes finished goods, work in process, and raw materials. You have completed the inventory count procedures and are happy that the inventory quantities are correct. You are also happy that the cost of each product line has been correctly calculated. You are now focused on assessing the net realizable value to establish if there is any need for an inventory writedown. Which of the following procedures should you carry out to satisfy yourself that inventory is recorded at the lower of cost and net realizable value?

a. Review sales after the end of the reporting period.

b. Observe deterioration or obsolescence during the auditor's attendance at the physical count.

c. Confirm inventories at outside locations.

d. Recalculate totals and extensions of quantities times unit prices.

e. Make inquiries of management and of sales and production personnel.

f. Review the minutes of the board of directors and executive committees.

g. Examine supplier invoices for purchased inventories.