One benefit of creating user stories that the business analyst can share with the executive sponsor is that it saves time when prioritizing and implementing functionality. User stories are short and simple descriptions of a feature or functionality from the perspective of an end user or customer. User stories help to capture the value and benefits of a solution, rather than the technical details or specifications. User stories also help to facilitate communication and collaboration among stakeholders, developers, and testers. User stories can save time when prioritizing and implementing functionality because they can be easily ranked or ordered based on their importance, urgency, dependency, or impact. User stories can also save time when implementing functionality because they can be easily translated into development tasks, acceptance criteria, and test cases.
References: https://trailhead.salesforce.com/content/learn/modules/user-story-creation/write-user-stories

Explanation
A storyboarding session is a technique to help stakeholders visualize how a solution will work by creating sketches or mockups of the user interface and interactions. This can help stakeholders understand the benefits and challenges of the proposed solution and provide feedback. A UPN diagram is a process modeling technique that shows the flow of activities and decisions, but it does not show how Marketing Cloud uses insights to create journeys. A capability model is a strategic tool that shows the high-level capabilities of an organization, but it does not show how a specific solution works. References: 1
https://trailhead.salesforce.com/en/content/learn/modules/salesforce-business-analyst-certification-prep/get-start

these are the characteristics that make a user story successful, according to the INVEST acronym. A user story should be independent of other user stories, negotiable in terms of scope and details, valuable to the user or customer, estimable in terms of effort and time, small enough to fit in a sprint or iteration, and testable with clear acceptance criteria. References:
https://trailhead.salesforce.com/content/learn/modules/user-story-creation/learn-about-user-stories

This answer chooses user stories as the element that the BA should use to define the intended results of the work based on stakeholder needs. User stories are short and simple descriptions of a feature or a functionality from the perspective of an end user or a stakeholder. User stories can help the BA define what stakeholders want to accomplish, why they want to accomplish it, and how they will measure success. User stories can also help the development and implementation teams to plan product decisions based on stakeholder value.
References:
https://trailhead.salesforce.com/en/content/learn/modules/salesforce-business-analyst-quick-look/use-user-stories