Microsoft SharePoint Restricted Content Discovery (RCD) provides a site-specific mechanism for limiting how SharePoint content appears in organization-wide Microsoft 365 search and Microsoft 365 Copilot experiences.

Option B is correct because the administrator can apply Restricted Content Discovery directly to Site1 without modifying the search behavior of the other 999 SharePoint sites.

When RCD is enabled for Site1, its content is generally excluded from organization-wide discovery experiences and Copilot responses. This reduces the risk of confidential documents appearing in broad search results.

Restricted Content Discovery does not modify existing SharePoint permissions or remove files from the Microsoft 365 search index.

Option A is incorrect because Restricted SharePoint Search uses a tenant-wide allowlist approach and can affect search results across many SharePoint sites. Microsoft also began blocking new enablement of that feature on July 31, 2026.

Option C is incorrect because Copilot connectors integrate external data sources rather than restrict the discovery of existing SharePoint content.

Option D is incorrect because Microsoft Search bookmarks promote selected resources rather than restrict document discoverability.

Implementation qualification: Microsoft documents exceptions for content users own or have recently interacted with. RCD is not an absolute security boundary. If all access must be prevented, SharePoint permissions or Restricted Access Control must also be considered.

Microsoft References:

https://learn.microsoft.com/en-us/sharepoint/restricted-content-discovery

https://learn.microsoft.com/en-us/sharepoint/restricted-sharepoint-search