The Product Owner is accountable for the functionality included in each Increment.

TheScrum Guideclarifies that the definition of "Done" is a shared commitment created by the Scrum Team: "The Definition of Done is a formal description of the state of the Increment when it meets the quality measures required for the product." While the Product Owner defines what goes into the Increment (via the Product Backlog), the definition of "Done" is a collaborative effort, often driven by the Developers’ technical expertise and organizational standards, with input from the Product Owner on value and quality expectations. Option A incorrectly gives the Product Owner sole authority, while B correctly reflects the team’s collective responsibility, with the Product Owner as a contributor, not the final arbiter.