______ allows a user to authenticate him or herself to the identity management server once; thereafter, whenever the user asks for access to another server, no additional logins are required.

• A. None of the above
• B. SSO
• C. RSO
• D. TSO

Answer: (B)

Single Sign-On lets a user authenticate once to a central identity management server and then access multiple servers or services without re-entering credentials for each one. After that initial login, the identity provider issues a token or assertion that other services trust, so the user can access them seamlessly during the session. This centralizes authentication, makes it easier to enforce security policies, and reduces the need to remember and repeatedly type passwords. The scenario described fits SSO precisely: a single login grants ongoing access to multiple resources without additional logins. Other terms don’t describe this behavior, so they don’t fit as well. In practice, SSO is implemented using protocols like SAML, OAuth, or OpenID Connect, enabling trusted communication between the identity provider and the various service providers.