Which of the following are true about the length of the Sprint? (Choose the best answer).

A、All Sprints must be one month or less.
B、The length of the Sprint should be proportional to the work that is Done in between Sprints.
C、Sprint length is determined during Sprint Planning, and should be long enough to make sure the Scrum Team can deliver what is to be accomplished in the upcoming Sprint.
D、Sprint length is determined during Sprint Planning, and should hold the time it will take to build the planned features in the upcoming Sprint, but does not include time for any testing.