Which of the following services does Frontier Airlines charge for?

Frontier Airlines operates under a low-cost model, which means that many services typically included in the price of a ticket with other airlines are not included in their fare structure. Seat selection and carry-on baggage are explicitly part of those additional services that Frontier charges for.

Passengers flying with Frontier can choose their seats for a fee, which allows for a degree of customization based on personal preference. Additionally, Frontier has a policy regarding carry-on baggage that differentiates it from many other airlines; while a personal item is included in the fare, a larger carry-on bag incurs an additional charge. This model helps keep base fares low, which is a fundamental aspect of Frontier's business strategy aimed at providing budget-friendly travel options.

In contrast, in-flight meals and entertainment, while also not included in the base fare, are more associated with in-flight offerings rather than service fees for baggage and seat selection. Flight delays and cancellations do not incur additional charges; they fall under operational issues. Discounted hotel stays and rental cars are ancillary partnerships or services that others might offer but are not direct charges from Frontier Airlines.