You attempt to build an OSPF virtual link between two ABR routers and it fails to form.
What are three explanations for this? (Choose three.)

A.
Both routers must share a common area.

B.
An adjacency exists with secondary IP addressing.

C.
An adjacency exists over an asynchronous interface.

D.
The transit area cannot be a stub area.

E.
One of the ABRs must be connected to area 0.