According to RFC 3931，L2TPv3 utilizes the IANA assigned IP protocol ID of（）.

A.None of the above.
B.The IP address 50.0.0.1/32 is assigned to the non-directly connected LDP neighbor， 50.0.0.4.
C.The IP address 50.0.0.1/32 is assigned to one of its own interfaces.
D.The IP address 50.0.0.1/32 is assigned to its directly connected LDP neighbor， 50.0.0.4.

A.Configure OSPF between trigger router and black hole routes
B.Configure all edge routers with static （reserved） host route to Null0
C.Configure BGP beteen trigger and black hole routers
D.Configure on trigger router to advertise victim host route with commumity
E.Activate black hole by redistributing route for victim into BGP with next-hop set to the static（reserved）host route configured on edge routers