This answer states that reviewing these user stories in the backlog at the next sprint retrospective is what the BA should do next after discovering that a few user stories are no longer needed for revamping the order management process at NTO. User stories are short descriptions of a feature or a functionality from a user's perspective. Backlog is a list of user stories that need to be prioritized and completed for a project or a product. Sprint retrospective is a meeting or a workshop where the project team reviews and reflects on their performance and progress in the previous sprint. Reviewing these user stories in the backlog at the next sprint retrospective means that the BA discusses and evaluates these user stories with the project team to determine if they are still relevant, valuable, or feasible for revamping the order management process. Reviewing these user stories in the backlog at the next sprint retrospective is what the BA should do next after discovering that a few user stories are no longer needed because it helps the BA to update and maintain the backlog, and to ensure that the user stories align with the project scope and goals. References: https://trailhead.salesforce.com
/en/content/learn/modules/salesforce-business-analyst-quick-look/use-user-stories-to-capture-requirements

Explanation
This answer suggests researching third-party apps on the AppExchange as the next thing that the BA should do after a sales manager expresses frustration that the sales team is failing to enter calls in Salesforce, and hopes to resolve the issue quickly and has limited time and budget to complete revamp existing tools and process.
The AppExchange is an online marketplace where customers can find, try, buy, and install apps that extend the functionality of Salesforce. Researching third-party apps on the AppExchange can help the BA to find a possible solution that can address the issue of entering calls in Salesforce without requiring a lot of time, budget, or customization. Researching third-party apps on the AppExchange can also help the BA to compare different features, prices, ratings, and reviews of various apps that can meet the sales manager's needs and expectations. References:
https://trailhead.salesforce.com/en/content/learn/modules/salesforce-business-analyst-quick-look/use-stakeholder

The type of research that the business analyst should use to elicit user stories from UC's customers is interviewing. Interviewing is a technique that involves asking open-ended questions to stakeholders or users to gather information and feedback about their needs, expectations, preferences, pain points, goals, etc.
Interviewing helps to elicit user stories from UC's customers by allowing them to express their opinions and experiences in their own words, as well as clarifying any doubts or ambiguities. Interviewing also helps to build rapport and trust with the customers and show them respect and appreciation for their input. References:
https://trailhead.salesforce.com/content/learn/modules/salesforce-business-analyst-certification-prep/customer- discovery

This answer states that asking for specific examples to review is how the BA should respond to feedback from UC's project manager who tells the BA that the developers on the team are having trouble understanding what to build because the acceptance criteria for the Sales Cloud user stories are confusing. Asking for specific examples to review means that the BA requests the project manager or the developers to provide concrete instances or scenarios of where and how the acceptance criteria for the Sales Cloud user stories are confusing, such as ambiguous, inconsistent, or incomplete acceptance criteria. Asking for specific examples to review is how the BA should respond to feedback from UC's project manager because it helps the BA to clarify and verify the feedback, and to revise and update the acceptance criteria accordingly. References: https://trailhead.
salesforce.com/en/content/learn/modules/salesforce-business-analyst-quick-look/use-stakeholder-engagement- skills