What ports generally need to be opened to allow this traffic to pass?

A Security Manager needs to allow L2TP traffic through the firewall into the Internet network. What ports generally need to be opened to allow this traffic to pass?

A.
TCP/UDP 1207

B.
TCP/UDP 500

C.
IP 50, IP 51

D.
TCP 49

E.
UDP 1701

F.
TCP 1072