Refer to the exhibit.

You must ensure that both core A and core B devices have only the minimum information required
for reaching the spoke routers yet maintain full reachability during network failures.
Which of the following design solutions accomplishes these requirements?

A.
Route summarization, with specific route leaking on hubs A and B

B.
Route summarization, with GRE tunnel on hubs A and B

C.
Implement PfR enhancements on hubs A and B.

D.
Implement ODR for hub-to-spoke routing.