Refer to the exhibit. 
Which statement is true?
A.
IS-IS has been enabled on R4 for IPv6, single-topology.
B.
IS-IS has been enabled on R4 for IPv6, multitopology.
C.
IS-IS has been enabled on R4 for IPv6, single-topology and multitopology.
D.
R4 advertises IPv6 prefixes, but it does not forward IPv6 traffic, because the protocol has not
been enabled under router IS-IS.