According to the Scrum Guide 1 , each Sprint is a project with no more than a one-month horizon. The Sprint Goal gives guidance to why the Scrum Team is building an Increment. The Development Team consists of professionals who do the work of delivering a potentially releasable Increment of "Done" product at the end of each Sprint. Therefore, in the first Sprint, as in any other Sprint, the Development Team should develop at least one piece of functionality and create an increment of potentially releasable software. The other options are not consistent with Scrum values and principles.
References: Scrum Guide

There are no activities that a Product Owner would typically undertake in the phase between the end of the current Sprint and the start of the next Sprint, because there is no such phase. The next Sprint starts immediately after the current Sprint, without any gaps or breaks. The other options are either activities that occur during a Sprint (such as refining the Product Backlog) or activities that are not consistent with Scrum (such as working with Quality Assurance departments or updating project plans).

According to the Scrum Guide 1 , the only required events in Scrum are Sprint Planning, Daily Scrum, Sprint Review, and Sprint Retrospective. These events enable transparency, inspection, and adaptation. The other options are not mandatory in Scrum, although they may be useful in some contexts.
References: Scrum Guide

The correct answer is C because the Daily Scrum is specifically an event for the Developers of the Scrum Team. According to the Scrum Guide, the Daily Scrum is held by the Developers to inspect progress toward the Sprint Goal and adapt the Sprint Backlog as necessary, adjusting the upcoming planned work. This makes the Developers the only people who must attend.
The Scrum Master's responsibility is to ensure that the event takes place and that attendees understand its purpose, but the Scrum Master is not required to attend unless they are actively helping the Developers or are also participating as part of the team's work. The Product Owner is also not required to attend. While either the Scrum Master or Product Owner may be present, the Daily Scrum remains a Developers' event.
Options A, B, D, and E are incorrect because they include roles that are not mandatory participants. Scrum is careful about this distinction to preserve self-management and ensure the Developers own daily planning. The Daily Scrum is not a status meeting for management or other roles. It is a focused inspection-and-adaptation event for the Developers.

According to the Scrum Guide 1 , the Development Team consists of professionals who do the work of delivering a potentially releasable Increment of "Done" product at the end of each Sprint. Development Teams are structured and empowered by the organization to organize and manage their own work. The resulting synergy optimizes the Development Team's overall efficiency and effectiveness. Cross-functional teams have all competencies needed to accomplish the work without depending on others not part of the team.
The team model in Scrum is designed to optimize flexibility, creativity, and productivity.
References: Scrum Guide