Which command enables IPv6 forwarding on a Cisco router?

Which command enables IPv6 forwarding on a Cisco router?

A.
ipv6 local

B.
ipv6 host

C.
ipv6 unicast-routing

D.
ipv6 neighbor

Explanation:
http://www.ciscopress.com/articles/article.asp?p=31948&seqNum=4