Delta Air Lines will radically change its SkyMiles frequent flier program next year, becoming the first of the "big three" U.S. airlines to ditch a fixed miles-for-a-free-flight system in favor of a supply-and-demand scheme that may require more mileage points to fly on more popular routes.
Utilize the input text as a context reference, choose the right relationship between 'SkyMiles' and 'Delta Air Lines' from the options.
Options: manufacturer, stock exchange, operator, developer