Which three features are common to OSPF and IS-IS?

Which three features are common to OSPF and IS-IS? (Choose three.)

A.
They both maintain a link-state database from which a Dijkstra-based SPF algorithm computes a
shortest path tree.

B.
They both use DR and BDR in the broadcast network.

C.
They both use hello packets to form and maintain adjacencies.

D.
They both use NSSA and stub type areas to scale the network design.

E.
They both have areas to form a two-level hierarchical topology.