According to the Professional Scrum Product Owner II certification guide1, the Product Owner is accountable for maximizing the value of the product resulting from the work of the Scrum Team. This means that the Product Owner is responsible for defining, ordering, and validating what the Scrum Team works on, and ensuring that the product delivers value to the customers, users, and the organization. The other options are not the most important thing a Product Owner can do, because they are either too narrow (A), too unrealistic (B), or too prescriptive . References: 1: Professional Scrum Product Owner II Certification | Scrum.org