What does it mean to say that an event has a time-box?

What does it mean to say that an event has a time-box?
A . The event must happen at a set time.
B . The event must happen by a given time.
C . The event must take at least a minimum amount of time.
D . The event can take no more than a maximum amount of time.

Answer: D

Explanation:

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.

Reference: Scrum Guide