Which statement is true about implementing a hub-and-spoke overlay VPN?

A.
A hub-and-spoke overlay VPN has no single point of failure.

B.
A spoke site has direct connectivity to the other spoke sites.

C.
If a dynamic routing protocol like RIP is used, split horizon mist be disabled at the hub router, or point-to-point sub-interfaces must be used.

D.
The total number of virtual circuits required to implement a hub-and-spoke overlay VPN is N(N-1)/2 where N = number of sites.

Explanation:

If a dynamic routing protocol such as RIP is used, split-horizon updates must be disabled at the hub router or point-to-point subinterfaces must be used at the hub router to overcome the split-horizon problem.
Reference: Cisco Press – Implementing Cisco MPLS study guide p.4-36