Which IPV6 scope prefix should you use?

Your network contains an Active Directory domain named contoso.com. The domain contains a server named
Server1 that runs Windows Server 2012 R2 and has the DHCP Server server role installed.
You need to create an IPv6 scope on Server1. The scope must use an address space that is reserved for
private networks. The addresses must be routable.
Which IPV6 scope prefix should you use?

A.
2001:123:4567:890A::

B.
FE80:123:4567::