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 to collaborate 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
