The requirement is explicit: users must have access to the Researcher agent in Microsoft 365 Copilot and use it to search across organizational content stored in SharePoint. Microsoft's licensing guidance for Researcher indicates that Researcher is available to Microsoft 365 business and enterprise users who have a Microsoft 365 Copilot add-on license (and also to certain consumer ''Microsoft 365 Premium'' subscriptions).

That maps directly to option C. The Researcher agent is part of the Microsoft 365 Copilot experience for work tenants; it is not enabled merely by having a baseline Microsoft 365 subscription entitlement (B). Baseline subscriptions can provide access to Microsoft 365 apps and content repositories (like SharePoint/OneDrive), but the Researcher agent itself is a Copilot capability that requires the Copilot add-on to unlock.

Option A (pay-as-you-go) and D (usage-based consumption license in Azure) describe consumption models that apply to Azure services or agent metering in some scenarios, but they are not the standard licensing requirement to enable the built-in Researcher agent for Microsoft 365 Copilot users. When the goal is to enable Researcher inside Microsoft 365 Copilot for staff, the practical and correct recommendation is to assign the Microsoft 365 Copilot per-user add-on license to the users who need it, ensuring their SharePoint access is already properly permissioned and governed.