Wal-Mart created a competitive advantage with its inventory system to reduce the ratio of cost of goods sold to sales, expecting:

a. to enjoy huge economic profits forever.
b. that its rivals will never imitate their strategy and it will continue to enjoy positive economic profits.
c. that its rivals will immediately do the same thing and it will end up earning zero profits.
d. to enjoy economic profits for a few years before its rivals caught up.
e. that it will at least be able to cover its fixed costs.

d