According to the Scrum Guide, the Scrum Team consists of one Scrum Master, one Product Owner, and Developers. There is no distinction between different types of Developers, such as testers, programmers, designers, etc. The Developers are the people who deliver a potentially releasable Increment of "Done" product at the end of each Sprint. They are accountable for creating and adhering to the Definition of Done, ensuring technical excellence and good design, and collaborating with the Product Owner to maximize value1.
Therefore, everyone on the Scrum Team is responsible for ensuring the quality of the product, and there is no specific tester role. However, this does not mean that testing skills are not needed or valued. On the contrary, testing is an essential activity that supports the team and critiques the product throughout the development process2. A professional tester can contribute to the Scrum Team by coaching the team on testing techniques, tools, and practices, helping the team to define clear and unambiguous acceptance criteria, challenging the team to consider different scenarios and edge cases, creating and executing test plans, and providing feedback on the product's usability, performance, security, and other aspects3. A professional tester can also collaborate with the Product Owner to ensure that the product meets the expectations and needs of the stakeholders and users.

Explanation
In Scrum, there is no separate artifact called a project plan. The Product Backlog is the plan for the product development, and it contains all the features, requirements, enhancements, and fixes that are needed to deliver a valuable product. The Product Backlog is not a static or fixed document, but rather an emergent and dynamic one. It is constantly updated and refined by the Product Owner and the Developers as they learn more about the product, the users, the market, and the technology. The Product Backlog is updated whenever new information and insights emerge, which can happen at any time during the product development process.
Therefore, option C is the best answer.
Option A is not correct because the Daily Scrum is not a status meeting, but rather a time-boxed event for the Developers to inspect their progress towards the Sprint Goal and adapt their Sprint Backlog accordingly. The Product Owner does not need to update the Product Backlog after the Daily Scrum, unless there is a significant change in the product vision, strategy, or value proposition that affects the Product Backlog items.
Option B is not correct because the Sprint Retrospective is not a time to update the Product Backlog, but rather a time-boxed event for the Scrum Team to inspect their way of working and identify potential improvements.
The Product Owner does not need to update the Product Backlog before the Sprint Retrospective, unless there is a need to communicate a change in the Product Goal or the product roadmap that affects the Product Backlog items.
Option D is not correct because the Sprint Planning is not a time to know how much work will have to be done in the Sprint, but rather a time-boxed event for the Scrum Team tocollaborate on selecting and planning the Product Backlog items that will deliver the Sprint Goal. The Product Owner does not need to update the Product Backlog before the Sprint Planning, unless there is a need to reorder or clarify the Product Backlog items that are the most valuable and relevant for the upcoming Sprint. References:
* Professional Scrum Product Owner II Assessment
* Understanding and Applying the Scrum Framework
* Managing Products with Agility
* What is a Product Backlog?
* Product Backlog Explained

Option B is the best answer because it reflects the agile and empirical nature of Scrum and Product Ownership. The Product Backlog is a living artifact that represents the current understanding of what the product needs to be most valuable for the customers and the stakeholders1. The Product Backlog is not a fixed or static document, but rather an emergent and dynamic one that adapts to the changing environment, needs, and feedback. The Product Owner is accountable for managing the Product Backlog and ensuring that it is transparent, ordered, and refined2. The Product Owner collaborates with the Scrum Team and the stakeholders to inspect and adapt the Product Backlog items based on the new insights, opportunities, and learnings that arise from the changing environment34. The Product Owner also uses various techniques, such as product vision, value proposition, user stories, experiments, and evidence-based management, to define, validate, and prioritize the Product Backlog items5 .
Option A is not the best answer because it contradicts the agile and empirical nature of Scrum and Product Ownership. The Product Backlog is not a requirements specification document, but rather a list of hypotheses and assumptions that need to be tested and validated in the real world5. The Product Backlog items are not detailed or fixed upfront, but rather refined and clarified as they get closer to implementation2. Updating the requirements specification document to ensure stability implies a plan-driven and predictive approach that does not embrace change and feedback, and that does not optimize value delivery.
Option C is not the best answer because it contradicts the agile and empirical nature of Scrum and Product Ownership. The Product Backlog is not a project plan, but rather a product roadmap that guides the development of the product. The Product Backlog does not have a predefined end date or scope, but rather evolves and changes as the product grows and matures1. Keeping the Product Backlog the same until the end of the project implies a plan-driven and predictive approach that does not embrace change and feedback, and that does not optimize value delivery.
Option D is not the best answer because it contradicts the agile and empirical nature of Scrum and Product Ownership. The Product Backlog is not a disposable artifact, but rather a cumulative and iterative one that builds on the previous work and learnings1. The Product Backlog items are not discarded or replaced, but rather refined and updated as the product evolves and changes2. Archiving the Product Backlog and creating a new one implies a disruptive and wasteful approach that does not leverage the existing knowledge and feedback, and that does not optimize value delivery.
Reference:
1: Product Backlog
2: Product Backlog Management
3: Empiricism
4: Stakeholders & Customers
5: Product Vision
6: Product Value
7: Evidence-Based Management
8: [Agile Manifesto]
9: [Product Roadmap]
10: Product Owner Accountabilities
11: Sprint Review
12: Product Backlog Refinement
13: [User Stories]
14: [Value Proposition]
15: [Experiments]

D is correct because the timebox for the Sprint Review is four hours or less for a one-month Sprint, and usually shorter for shorter Sprints1. The Sprint Review is an event where the Scrum Team and the stakeholders inspect the outcome of the Sprint and collaborate on what to do next1. A is incorrect because the Sprint Review is not an open-ended event, but a timeboxed one that respects the attendees' time and ensures productivity2. B is incorrect because the Sprint Review is not a point in time, but a timeboxed event that has a specific purpose and agenda1. C is incorrect because the Sprint Review is not the same as the Daily Scrum, which is a 15-minute event for the Developers to synchronize their work1.