Two techniques that would be most helpful in this situation are to discuss the impediments with the Development Team, and to prioritize the list and work on them in order, as stated in [3]: "The Scrum Master should facilitate a discussion with the Development Team to identify and prioritize the impediments that are blocking their progress. The Scrum Master should then work with the Development Team and other stakeholders to remove or mitigate these impediments as soon as possible."

According to the Scrum Guide, three behaviors that demonstrate that a team is self-organizing are creating their own sprint backlog, having all the skills needed to create a releasable Increment, and collaboratively selecting their own work during the Sprint. The other options are not behaviors that demonstrate self-organization, as they are either contrary to Scrum values and principles (such as stakeholders walking in at the Daily Scrum or working within functional boundaries) or unnecessary for self-organization (such as the Product Owner not being at Sprint Retrospectives or the Development Team inviting external people to the Sprint Planning).

According to the Scrum Guide 1 , Scrum does not require or provide any specific techniques or methods for product definition. Rather, Scrum provides a framework with roles, rules, and events within which complex products can be developed. To get started in terms of what to build, Scrum requires no more than a Product Owner with enough ideas for a first Sprint, a Development Team to implement those ideas and a Scrum Master to help guide the process.
References: Scrum Guide

The correct answer is C, because the Scrum Guide states that "the Scrum Master ensures that the Development Team has the meeting, but the Development Team is responsible for conducting the Daily Scrum. The Scrum Master teaches the Development Team to keep the Daily Scrum within the 15-minute time-box." Therefore, the main reason for the Scrum Master to be at the Daily Scrum is to ensure that it happens, but he or she does not have to be there.

The Product Owner is responsible for ensuring that the most valuable functionality is produced first, at all times, by ordering and prioritizing the Product Backlog. The Product Owner also interacts with stakeholders to understand their needs and expectations, and to communicate the vision and progress of the product. The other options are not part of the Product Owner role according to Scrum, as they are either too prescriptive or too technical.