What is single sign-on? An authentication method:

A.
that allows users to authenticate once, and then uses tokens or other credentials to manage subsequent authentication attempts

B.
that stores user credentials locally, so that users need only authenticate the first time, a local machine is used

C.
requiring the use of one-time passwords, so users authenticate only once, with a given set of credentials.

D.
that uses smart cards, hardware tokens, and biometrics to authenticate users; also known as three-factor authentication

E.
that requires users to re-authenticate for every resource accessed