Which of the following is (are) true of the Dollar General competitive strategy and/or its results?
a. its start - up costs are lower than those of Wal - Mart
b. its sales per square foot are higher than those of Wal - Mart
c. despite its advantages, it must still anticipate that Wal - Mart could become a formidable competitor
d. a and b
e. a, b, and c