Which statement is true regarding the SPF algorithm?

A.
The SPF algorithm is run on a per-domain basis.

B.
If you apply an import policy to OSPF, it keeps LSAs from being flooded, and the SPF
calculation can be affected.

C.
There are two databases used in the calculation, the link-state database and the tree
database.

D.
The SPF calculation is run on a per-area basis on each router.