Explanation
As a Product Owner, you are accountable for maximizing the value of the product and the work of the Scrum Team. To do this, you need to collaborate with various stakeholders, user communities and other Product Owners to understand their needs, expectations and feedback, and to align them with the product vision and strategy. You also need to work with the Developers on Product Backlog refinement, which is an ongoing activity to add detail, estimates and order to Product Backlog items. This helps the Developers to understand what is valuable and feasible to deliver in the upcoming Sprints, and to plan and execute their work accordingly. These are typical and essential work for a Product Owner in a Sprint.
The other options are not typical or effective work for a Product Owner in a Sprint. Attending every Daily Scrum is not necessary, as the Daily Scrum is an event for the Developers to inspect their progress and plan their next steps. The Product Owner can attend the Daily Scrum if invited by the Developers, but should not interfere or answer questions that are not related to the Sprint Goal or the Product Backlog. Creating financial reporting upon the spent hours reported by the Developers is not a valuable activity, as it does not reflect the outcome or the value delivered by the product. It also goes against the Scrum values of trust and respect, as it implies that the Developers are not self-managing or committed to their work. Updating the work plan for the Developers on a daily basis is also not a good practice, as it undermines the autonomy and creativity of the Developers, and reduces their ability to inspect and adapt their work based on the empirical evidence. The Product Owner should not tell the Developers how to do their work, but rather focus on what is the most valuable outcome for the product.
References:
* Professional Scrum Product Owner™ II Certification
* Understanding and Applying the Scrum Framework
* Managing Products with Agility

Explanation
= As a Product Owner, you are accountable for maximizing the value of the product and the work of the Developers. To do this, you need to have a clear vision of the product and its target users, as well as a validated understanding of the market opportunities and risks. You also need to collaborate with stakeholders and customers to align their expectations and feedback with the product goals and strategy.
In this scenario, you face a dilemma between pursuing a new market segment or satisfying the existing customers. Both options have potential value, but also uncertainty and trade-offs. The best way to proceed is to devise an experiment that will help you to test your assumptions and learn more about the new market and its potential. This could be a small-scale release, a prototype, a survey, or any other method that can provide you with empirical evidence and feedback. By doing this, you can reduce the risk of investing in a feature that may not deliver the expected value, and also gain insights that can help you to refine your product vision and backlog.
This approach is consistent with the principles of agile product management, which emphasize delivering value early and often, validating hypotheses with data, and adapting to changing customer needs and market conditions. It also demonstrates your ability to apply the Scrum values of openness, courage, and respect, as you are willing to explore new possibilities, challenge your own opinions, and involve your stakeholders and customers in the decision-making process. References := Scrum Guide, Managing Products with Agility, Evidence-Based Management

According to the Professional Scrum Product Owner II guide, one of the key competencies of a Product Owner is to validate product assumptions and hypotheses using empirical evidence1. This means that instead of investing a lot of money and time into building a product based on unproven ideas, the Product Owner should conduct small experiments to test the viability, desirability, and feasibility of the product2. These experiments can take various forms, such as prototypes, mockups, surveys, interviews, landing pages, etc. The goal is to gather feedback from real or potential users and customers, and measure the outcomes against predefined success criteria3. Based on the results of the experiments, the Product Owner can then decide whether to persevere, pivot, or terminate the product idea4. This approach helps to reduce the risk of wasting resources on products that nobody wants or needs, and to focus on the most valuable and promising ideas.