Which of the following descriptions of single sign-on is correct?

Which of the following descriptions of single sign-on is correct?
A . The visitor recited the Portal authentication page and sent the username and password to FT to identify his/her identity, and the password was not stored on the FT, and the FI sent the username and password to the third-party authentication server, and the authentication process was carried out on the authentication server.
B. The visitor sends the username and password that identifies his identity to the third-party authentication server, and after the authentication is passed, the third-party authentication server sends the visitor’s identity information to FW. F7 only records the identity information of the visitor and does not participate in the authentication process
C. Visitors obtain the SMS verification code through the Portal authentication page, and then enter the SMS verification code to pass the authentication.
D. The visitor sends the username and password that identifies them to the FW through the portal authentication page, on which the password is stored and the verification process takes place on the FW.

Answer: B