To enable social sign-on for Experience Cloud, Salesforce expects the architect to create an authentication provider for each social identity source, expose those providers on the login page, and use the registration handler logic that creates or updates the external user in Salesforce. SAML federation is not required for Facebook or LinkedIn sign-in. Connected apps are not how those social providers are registered for Experience Cloud login; the trust is established through authentication providers. The architect also needs the login page to actually show the provider buttons so users can choose those sign-in methods. In short, the implementation has three moving parts: provider setup, login-page exposure, and user-provisioning logic through the registration handler. This is why options A, C, D work together as the correct solution.