Which of the following is a protocol used to implement virtual private networks $($VPNs$)$ using a control channel over Transmission Control Protocol $($TCP$)$ and a Generic Routing Encapsulation $($GRE$)$ tunnel for data? It does not provide encryption.

A$.$ Layer $2$ Forwarding $($L$2$F$)$

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

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

D$.$ Internet Protocol Security $($IPSec$)$