Refer to the exhibit.

Which interoperability technique implemented on the dual-stack routers would
allow connectivity between IPv6 sites across automatic created tunnels using the 2002::/16 prefix?

A.
Dual Stack

B.
NAT-PT

C.
6to4 tunnel

D.
GRE tunnel

E.
ISATAP tunnel

Explanation:
http://hcc.dormv6.niu.edu.tw/~hccftp/journal30.pdf (page 166, see Table 1)