Which major airlines does Republic Airways operate flights for?

Republic Airways is a regional airline that primarily operates under the brands of American Airlines, United Airlines, and Delta Air Lines. These major carriers partner with Republic Airways to provide regional service, commonly using smaller aircraft to connect passengers to larger hubs. This relationship is part of a larger code-sharing agreement, allowing these airlines to expand their route network without directly operating all the flights themselves. The significance of this arrangement lies in enabling airlines to offer a wider range of destinations and improve overall service to their customers.

The other options reflect airlines that do not have operational partnerships with Republic Airways, which is why they are not the correct choice in this context.