Who is accountable for creating a plan for the Sprint and adhering to the Definition...

According to the Scrum Guide, the Developers are the people in the Scrum Team who are committed to creating any aspect of a usable Increment each Sprint. They are accountable for creating a plan for the Sprint, the Sprint Backlog, and for adhering to the Definition of Done. The Product Owner and the Scrum Master are not accountable for these activities, but they may support the Developers as needed. The Scrum Team as a whole is accountable for delivering a valuable, useful, and potentially releasable Increment each Sprint, but the Developers have the specific accountability for planning and building it. References := Scrum Guide, Understanding and Applying the Scrum Framework, Managing Products with Agility