In Kerberos, the Ticket-Granting Ticket (TGT) is the feature that enables single sign-on (SSO). After initial authentication, the user receives a TGT from the Key Distribution Center (KDC). The TGT is then used to obtain service tickets for accessing various resources without re-authenticating, providing a seamless SSO experience. Sign in with Apple at Work & School (option A) is an Apple-specific feature, not a Kerberos component. OAuth (option B) and SAML (option D) are separate SSO protocols, not Kerberos features. The Apple Platform Security Guide explains the TGT's role in Kerberos SSO.