The business analyst should review the version control history to understand which user stories were modified by the project lead. Version control is a system that records changes to a file or set of files over time so that you can recall specific versions later. Version control can help track who made what changes, when, and why.
It can also help compare different versions, merge changes, resolve conflicts, and restore previous versions.
The business analyst should use a version control system to store and manage their user stories in a repository and review the version control history to see the edits made by the project lead. Reviewing the approval history is not a good option because it would only show who approved or rejected the user stories, not who modified them or how. Reviewing the change sets history is not a good option because it would only show what metadata components were deployed or retrieved between orgs, not what user stories were modified or how. References:
https://trailhead.salesforce.com/en/content/learn/modules/org-development-model/get-to-know-org-development

A user story is a short, simple description of a feature told from the perspective of the person who desires the new capability, usually a user or customer of the system. It typically follows a simple template: As a <type of user>, I want <some goal> so that <some reason>. The answer C follows this template and clearly states the user role, the goal, and the reason. The answer A does not state the reason, and the answer B does not state the correct user role, as the story is about sales representatives, not sales managers. References: Certification - Business Analyst, Get Started with Salesforce Business Analyst Certification Prep, Cert Prep: Salesforce Business Analyst

Explanation
To successfully meet governance requirements to identify the business purpose, the business analyst should adhere to agreed upon mapping standards. Mapping standards are guidelines or conventions that define how to create and document business process maps. They help to ensure consistency, clarity, and quality of the process maps across different projects and teams. They also help to align the process maps with the business objectives and requirements, and support regulatory considerations.
References:https://trailhead.salesforce.com/content/learn/modules/salesforce-business-analyst-certification-prep/