The best answer is B. The Sprint length is unchanged and the Scrum Team continuously learns and adapts.
According to the Scrum Guide1, “Sprints have consistent durations throughout a development effort. A new Sprint starts immediately after the conclusion of the previous Sprint.” Therefore, the Sprint is not extended or shortened based on the completion of the work.
The Scrum Guide also states that “Scrum Teams deliver products iteratively and incrementally, maximizing opportunities for feedback. Incremental deliveries of ‘Done’ product ensure a potentially useful version of working product is always available.” Therefore, the Scrum Team should focus on delivering a potentially releasable Increment of value by the end of the Sprint, even if some work items are not completed.
The Scrum Team should also use the Sprint Retrospective to inspect how the last Sprint went with regards to individuals, interactions, processes, tools, and their Definition of Done. The Scrum Team should identify and order the major items that went well and potential improvements, and create a plan for implementing improvements to the way they do their work. This way, the Scrum Team continuously learns and adapts to changing circumstances and challenges.
