You administer a company's SharePoint Online environment. The environment hosts several site collections that are used to store documents that contain sensitive customer information. A user in the…

Sharing the entire site exposes all content within that site to external vendors, which is broader than necessary and risks unauthorized access to other sensitive customer documents.

Not requiring sign-in generates an anonymous access link that can be forwarded without restriction, providing no authentication audit trail and violating the security requirements of a sensitive environment.

Sharing an entire document library grants external vendors access to every document in that library, which exceeds the required scope and could expose additional sensitive files beyond the intended collaboration document.

Sharing the specific document rather than the site or library limits external vendor access to only the content they need, following the principle of least privilege and protecting the broader site collection that contains sensitive customer information. Requiring sign-in ensures each vendor authenticates with a verifiable identity, creating an audit trail and preventing the link from being forwarded to unauthorized parties. This combination enables collaboration on the target document while preserving the security posture of the overall environment.