Which one of the following is true about single sign-on?

Single Sign-On (SSO) is a mechanism that enables users to authenticate once and gain access to multiple independent software systems without re-entering credentials. Identity consolidation, while related, refers to the process of merging multiple disparate user identities into a single, unified identity store, which is a prerequisite or enabler for SSO but not SSO itself.

SSO aims to avoid sending the same credentials repeatedly to several services after the initial authentication; instead, it uses tokens or session management for subsequent access.

For effective SSO, credentials for different services often originate from a single identity provider and are thus unified, not distinct, from the user's perspective.

While smartcards can be used as an authentication factor within an SSO system, they are not a mandatory requirement for all SSO implementations.