Which of the following would a company implement to provide authentication to multiple websites that are delivered through PaaS?

Federation services enable single sign-on across distinct security domains, but RBAC is the specific mechanism used within a PaaS to control access to individual resources and applications once a user is authenticated to the platform's identity provider.

MAC (Mandatory Access Control) is a strict access control model not typically used for web application authentication in PaaS, and MAC addresses are physical network identifiers unrelated to web authentication.

Multi-factor authentication enhances the security of the authentication process but is not an access control mechanism for multiple websites itself.

Within a PaaS environment, RBAC allows administrators to assign specific roles to users, granting or denying them access to various resources, including multiple websites delivered as PaaS applications, after they have authenticated to the platform's identity provider.