A local ferry service offers a passenger boat trip that travels from Port A to...

A local ferry service offers a passenger boat trip that travels from Port A to Port B, and then back again, once a day. Passengers can book tickets using an app, and they often try to make last-minute reservations for the outbound trip. The ferry service wants their app to place a passenger on a waiting list for the first trip, while guaranteeing them a reservation for the second trip.

Which two case design patterns apply to this scenario? (Choose Two)