Which statement about scalability in Cisco OTV is true?

A.
The control plane avoids flooding by exchanging MAC reachability.

B.
IP-based functionality provides Layer 3 extension over any transport.

C.
Any encapsulation overhead is avoided by using IS-IS.

D.
Unknown unicasts are handled by the authoritative edge device.

Explanation:
Cisco calls the underlying concept of OTV traffic forwarding “MAC routing”, since it behaves as if you
are routing Ethernet frames over the DCI transport. OTV uses a control plane protocol to proactively
propagate MAC address reachability before traffic is allowed to pass, which eliminates dependency
on flooding mechanism to either learn MAC addresses or forward unknown unicasts.

http://www.computerworld.com/article/2515468/data-center/layer-2-data-center-interconnectoptions.html