The Product Owner should know the most about the progress toward a business objective or a release, as stated in the Scrum Guide: "The Product Owner is responsible for maximizing the value of the product resulting from work of the Development Team. How this is done may vary widely across organizations, Scrum Teams, and individuals."

According to the Scrum Guide1, the heart of Scrum is a Sprint, a time-box of one month or less during which a "Done", useable, and potentially releasable product Increment is created. Sprints have consistent durations throughout a development effort. A new Sprint starts immediately after the conclusion of the previous Sprint. The length of a Sprint should be short enough to keep the business risk acceptable to the Product Owner, short enough to be able to synchronize the development work with other business events, and no more than one calendar month.

During the Sprint Retrospective, the Scrum Team may add items to the Sprint Backlog for the next Sprint, as stated in [5]: "The purpose of each Sprint Retrospective is to plan ways to increase quality and effectiveness. The Scrum Team plans ways to implement improvements identified during this meeting into its way of working. By doing this it reinforces empiricism throughout its work. Improvements may be implemented at any time during a Sprint or they may be planned for subsequent Sprints."

A cross-functional Development Team is one that includes cross-skilled individuals who are able to contribute to do what is necessary to deliver an increment of software, as stated in the Scrum Guide1: "Cross-functional teams have all competencies needed to accomplish the work without depending on others not part of the team."

The answer is A. True. The Sprint Backlog is a result of Sprint Planning, and it includes the Sprint Goal. According to the Scrum Guide, the Sprint Backlog is composed of the Sprint Goal (why), the set of Product Backlog items selected for the Sprint (what), as well as an actionable plan for delivering the Increment (how)1. The Sprint Goal is the single objective for the Sprint, and it provides coherence and focus for the Scrum Team2. The Sprint Backlog is a plan by and for the Developers, and it is updated throughout the Sprint as more is learned2.