What is a virtual private network $($VPN$)$ protocol that requires public key infrastructure $($PKI$)$ support to obtain and use a certificate?

Group of answer choices

Internet Key Exchange v$2($IKEv$2)$

Layer $2$ Tunneling Protocol $($L$2$TP$)$

Point$-$to$-$Point Tunneling Protocol $($PPTP$)$

Secure Sockets Layer$/$Transport Layer Security $($SSL$/$TLS$)$