Which three of the following are time-boxed events in Scrum?

According to the Scrum Guide1, each event in Scrum is a formal opportunity to inspect and adapt something. These events are specifically designed to enable critical transparency and inspection. Failure to include any of these events results in reduced transparency and is a lost opportunity to inspect and adapt. All events are time-boxed events, such that every event has a maximum duration. Once a Sprint begins, its duration is fixed and cannot be shortened or lengthened. The remaining events may end whenever the purpose of the event is achieved, ensuring an appropriate amount of time is spent without allowing waste in the process. The time-boxed events in Scrum are:

Sprint Planning (eight hours or less for a one-month Sprint)

Daily Scrum (15 minutes or less for a one-month Sprint)

Sprint Review (four hours or less for a one-month Sprint)

Sprint Retrospective (three hours or less for a one-month Sprint)

The other options are not time-boxed events in Scrum.

References: Scrum Guide