B is correct because the Product Owner is accountable for maximizing the value of the product and the work of the Developers1, and delaying answers to the Developers can cause waste, rework, and missed opportunities2. E is correct because the Product Owner is responsible for ensuring that the product Increment is valuable and useful for the stakeholders and customers3, and this requires close collaboration and feedback with the Scrum Team and the users4. A is incorrect because the Product Owner does not need to dedicate 100% of their time to the Scrum Team, as they also have other accountabilities such as engaging with the market, managing the product vision, and aligning with the business strategy5. C is incorrect because the Product Owner is not a proxy for the stakeholders, and they should not delegate their role to business analysts or anyone else. D is incorrect because the Product Owner does not need the approval of the stakeholders to decide how much time they spend with the Scrum Team, as they are empowered to make the best decisions for the product. F is incorrect because the Product Owner should not base their time allocation on the complaints of the Developers, but on the value and quality of the product.

A good Product Vision and Strategy should have the following attributes12:
It describes who will use the product and what they would like to achieve. This helps to define the target market, the customer segments, and the user personas, as well as their needs, goals, and problems.
It describes how people will use the product to achieve potential outcomes. This helps to articulate the value proposition, the benefits, and the features of the product, as well as the assumptions and hypotheses that need to be validated.
It describes what value means in the context of the product, and how it can be measured. This helps to establish the objectives, the key results, and the metrics that will guide the product development and evaluation.
It is not necessary for a good Product Vision and Strategy to describe how the product compares to competitor products. This may be part of the market analysis or the competitive advantage, but it is not a core attribute of the Product Vision and Strategy. Moreover, focusing too much on the competitors may distract from the customer needs and the product value. References: 1: Product Vision, 2: Product Strategy

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. Reference:
Professional Scrum Product Owner II Assessment
Understanding and Applying the Scrum Framework
Managing Products with Agility
What is a Product Backlog?
Product Backlog Explained