Choice "D" is correct. The pledge or assignment of any inventories should be appropriately disclosed in the financial statements.
Choice "c" is incorrect. Inventories should be reduced, when appropriate, to replacement cost or net realizable value, but this is more closely related to the valuation of inventory.
Choice "b" is incorrect. Consignment agreements should be examined to ensure that the entity has ownership rights to the inventory (and does not include inventory owned by others), but this relates to the rights and obligations assertion, not to classification and understandability assertions.
Choice "a" is incorrect. Inventory turnover is analyzed as a means of identifying slow-moving, excess, defective, or obsolete items included in inventory, but this relates more closely to the valuation of inventory.