According to an article in the Wall Street Journal, between 1998 and 2018, the number of nonstop coast-to-coast flights in the United States more than doubled at the same time that the price of a ticket declined. For each of the following scenarios, briefly explain whether the scenario can account for this outcome.
a. The demand for coast-to-coast flights decreased during this period, while the supply of flights increased.
b. The demand for coast-to-coast flights increased during this period, while the supply of flights decreased.
c. The demand for coast-to-coast flights and the supply of flights both increased during this period.
d. The demand for coast-to-coast flights and the supply of flights both decreased during this period.