Which command enables IPv6 forwarding on a Cisco router?

A.
ipv6 host

B.
ipv6 unicast-routing

C.
ipv6 local

D.
ipv6 neighbor

Explanation:
Enabling IPv6 on Cisco IOS Software Technology
http://www.ciscopress.com/articles/article.asp?p=31948&seqNum=4

The first step of enabling IPv6 on a Cisco router is the activation of IPv6 traffic
forwarding to forward unicast IPv6 packets between network interfaces. By default, IPv6 traffic
forwarding is disabled on Cisco routers.
The ipv6 unicast-routing command is used to enable the forwarding of IPv6 packets between
interfaces on the router.The syntax for this command is as follows:
Router(config)#ipv6 unicast-routing The ipv6 unicast-routing command is enabled on a global
basis.