which of the following is less likely to be used?

When creating a VPN, which of the following is less likely to be used?

A.
L2TP

B.
PPTP

C.
IPSec

D.
L2F

Explanation:
L2F (Layer 2 Forwarding) provides no authentication or encryption. It
was merged with PPTP into L2TP. IPSec is now considered an appropriate VPN solution
for IP environments.