A fundamental difference between U.S. GAAP and IFRS is that a. reversal of inventory write-downs is permitted under IFRS; however, reversal of inventory writedowns is prohibited under U.S. GAAP. b. distribution costs are included in cost of sales under U.S. GAAP; however, distribution costs are excluded from cost of sales under IFRS. c. inventory is generally valued at the lower of cost or market under IFRS; however, inventory is generally valued at the lower of cost or net realizable value under U.S. GAAP. d. marketing costs are included in cost of sales under U.S. GAAP; however, marketing costs are excluded from cost of sales under IFRS