A town with a small airport is served by two competing airlines. Which of the following strategies would make the airlines more likely to compete on price?
a) The airlines fly identical planes, with the same type of seat and the same amount of legroom for customers
b) One airline offers meals on board every flight while the other serves no meals but has fewer delayed flights
c) Each airline offers flights to a different set of other cities
d) The airlines offer loyalty programs, motivating existing customers to continue to fly with them