Which of these authentication combinations would provide the highest level of security for an IPsec remote-access VPN client?
A.
pre-shared key and xauth (RADIUS server)
B.
certificate and xauth (local server)
C.
certificate and xauth (RSA SecurID token)
D.
pre-shared key and xauth (RSA SecurID token)
E.
pre-shared key and xauth (local server)
F.
certificate and xauth (RADIUS server)