What is the method used by Sun Kerberos to protect user passwords?

A.
User passwords are encrypted when sent to the authenticating Key Distribution Center (KDC) server.

B.
User passwords are sent only after the Key Distribution Center (KDC) server and client have established an IPSec connection.

C.
User passwords are used only to decrypt the secret key sent from the authenticating Key Distribution Center (KDC) server.

D.
User passwords are used to encrypt the user name, which is then sent to the authenticating Key Distribution Center (KDC) server.