Refer to the exhibit.

Your customer has enabled IPv6 and IPv4 on routers R1 and R2, both
running ISIS routing protocol, and they can no longer reach R3 network 172.26.15.0/24 (R3 does
not enable IPv6, enables IPv4 only). Which two steps should be taken to restore reach ability to R3? (Choose two.)

A.
Enable OSPFv3 to support IPv4 and IPv6 simultaneously.

B.
Configure static routes to all unreachable networks and redistribute to IS-IS.

C.
Create an IPv6 tunnel from R2 to R3.

D.
Transition to IS-IS Multiple Topology Mode on R3.

E.
Enable wide metrics.

F.
Transition to IS-IS Multiple Topology Mode on R1 and R2.