Ilsia is driving home from work. She needs to buy gas and notices an Exxon-Mobil station on one side of the street and a Shell station on the other side of the street. Although run by different companies, the two stations sell gasoline at the same price. The most likely reason that
A. the price is the same is that drivers need gas and are willing to pay whatever price a gas station charges.
B. government regulation requires both gas stations to charge the same price.
C. consumers view gasoline from different gas stations as perfect substitutes.
D. gas stations always make a profit, so they can charge any price they want.