Select the answer that correctly completes the sentence.

In Microsoft identity and access scenarios, federation is explicitly defined as a mechanism to create trust between autonomous organizations so that identities authenticated in one can be accepted by another. Microsoft describes this as: “Federation is a collection of domains that have established trust.” In a federation, “this trust relationship lets each organization accept the other’s user authentication” and enables access to resources without the need to duplicate user accounts or require separate credentials. Within Azure AD/Microsoft Entra and AD FS guidance, Microsoft further explains that federation enables “claims-based access across security boundaries” and “allows users to access applications in a partner organization using their existing credentials.” These statements underline that the purpose of federation is to establish a trust relationship across identity providers or directories, not to provide multi-factor authentication, synchronize accounts, or build network tunnels. MFA is an authentication strength that can be applied on top of federated sign-in, user account synchronization is handled by services like Microsoft Entra Connect (Azure AD Connect), and VPNs provide network connectivity, not identity trust. Therefore, the completion that aligns with Microsoft SCI documentation is that federation establishes a trust relationship between organizations.