The Developers are the ones who are accountable for tracking the remaining work toward the Sprint Goal. The Developers are self-managing and decide how much work they can do in a Sprint1. They also create and update the Sprint Backlog, which is the plan for how the Developers will achieve the Sprint Goal, and the single source of truth for the work to be done in the Sprint2. The Developers use the Daily Scrum to inspect their progress toward the Sprint Goal and adapt the Sprint Backlog as necessary[3][3]. The Product Owner, the Scrum Master, and the Project Manager (if any) do not have the accountability for tracking the remaining work toward the Sprint Goal, as this is the responsibility of the Developers.
References:
1: The Scrum Guide, November 2020, p. 6
2: The Scrum Guide, November 2020, p. 10
[3][3]: The Scrum Guide, November 2020, p. 11

* The Sprint Review is an event that occurs at the end of each Sprint, where the Scrum Team and the stakeholders inspect the Increment and adapt the Product Backlog if needed. The Sprint Review is an opportunity for the Product Owner to validate that the Increment meets their expectations and delivers value to the customers and users. The Sprint Review is also an opportunity for the Developers to demonstrate their work and receive feedback from the Product Owner and the stakeholders.
* The purpose of a Sprint Review is to inspect the product Increment with the stakeholders and collect feedback on next steps. The Sprint Review is a collaborative and interactive session where the Scrum Team and the stakeholders discuss what was done in the Sprint, what problems were encountered, what was learned, and what can be improved or changed. The Sprint Review also provides input for updating the Product Backlog to maximize value in future Sprints.
* The other options are not valid or relevant purposes of a Sprint Review. They are either too vague, unrelated, or incorrect. They are:
* To build team spirit: This is not a valid purpose of a Sprint Review. While team spirit is important for any Scrum Team, it is not the main focus or outcome of a Sprint Review. A Sprint Review is a formal event that has a specific agenda and goal, not a casual or social gathering.
* To take time to judge the validity of the project: This is not a valid purpose of a Sprint Review.
Scrum does not have a concept of a project, but rather a product. A product is a valuable solution that evolves over time to meet customer needs and market conditions. A project is a temporary endeavor with a fixed scope, time, and cost. A Sprint Review is not a time to judge or evaluate the validity of the product or its development, but rather to inspect and adapt it based on empirical evidence and feedback.
* To review the Scrum Team's activities and processes during the Sprint: This is not a valid purpose of a Sprint Review. This is the purpose of another Scrum event called the Sprint Retrospective. The Sprint Retrospective is an event that occurs after the Sprint Review and prior to the next Sprint Planning, where the Scrum Team inspects how they worked during the Sprint and identifies improvements for the next Sprint. The Sprint Retrospective focuses on improving the Scrum Team's performance and process, not on inspecting the product Increment or its value.
References:
Scrum Guide: https://www.scrumguides.org/scrum-guide.html
Sprint Review: https://www.scrum.org/resources/what-is-a-sprint-review