The correct answer is B. data loss prevention (DLP) policies . Microsoft Learn states that Microsoft Purview Data Loss Prevention helps organizations identify, monitor, and automatically protect sensitive information across Microsoft 365 locations such as Exchange, SharePoint, OneDrive, Teams, and devices . Microsoft specifically documents scenarios for preventing sensitive items from being shared with external users in SharePoint and OneDrive, and DLP policies can also block or restrict sharing based on sensitive information types, labels, or policy conditions. This is exactly the control used when the requirement is to stop users from sharing corporate financial data outside the organization.

Option A is incorrect because retention labels manage how long content is kept or deleted, not whether it can be shared externally. Option C is incorrect because role groups are used for permissions and administrative access delegation, not content-sharing prevention. Option D is incorrect because Insider Risk Management is designed to detect and investigate risky user behavior, not to directly block external sharing transactions in the way DLP policies do. For proactive enforcement of external-sharing restrictions on sensitive financial information, Microsoft’s documented solution is DLP policies .