Which of these may a Development Team deliver at the end of a Sprint?

The correct answer is C, because a Development Team should deliver an increment of working software that is “done” by the end of a Sprint. The Scrum Guide states that “the Increment is the sum of all the Product Backlog items completed during a Sprint and the value of the increments of all previous Sprints. At the end of a Sprint, the new Increment must be ‘Done,’ which means it must be in useable condition and meet the Scrum Team’s definition of ‘Done’.”