What Do Wal-Mart,the Microsoft Corporation,and the Dell Computer Company Have

What do Wal-Mart,the Microsoft Corporation,and the Dell computer company have in common?

A) Each achieved a dominant position in its industry because it owned a key input in the production of its product.
B) The industry in which each firm competes is an oligopoly because of government-imposed barriers to entry.
C) Each company was founded in the same state.
D) The profitability of each firm depends on its interactions with other firms.