What are two solutions to the problem?

Refer to the Exhibit.

You configure a network according to the topology shown in the exhibit but find that users attached to R7 are having difficulty communicating with the rest of the network.
What are two solutions to the problem? (Choose two.)

A.
Configure Area 3.3.3.3 as a stub area.

B.
Create a virtual link between R3 and R6.

C.
Configure an OSPF export policy on R6 to export routes from Area 2.2.2.2 to Area 3.3.3.3 and from Area 3.3.3.3 to Area 2.2.2.2.

D.
Connect R6 to Area 0.0.0.0.

Explanation:
Stub area

A stub area is an area which does not receive route advertisements external to the autonomous system (AS) and routing from within the area is based entirely on a default route. A Stub Area simulation shows how an ABR deletes type 4, 5 LSAs from internal routers, sends them a default route of 0.0.0.0 and turns itself into a default gateway. This reduces LSDB and routing table size for internal routers.

Modifications to the basic concept of stub areas exist in the not-so-stubby area (NSSA). In addition, several other proprietary variations have been implemented by systems vendors, such as the totally stubby area (TSA) and the NSSA not so stubby area, both an extension in Cisco Systems routing equipment.

Not-so-stubby area

A not-so-stubby area (NSSA) is a type of stub area that can import autonomous system external routes and send them to other areas, but still cannot receive AS-external routes from other areas. NSSA is an extension of the stub area feature that allows the injection of external routes in a limited fashion into the stub area. A case study simulates an NSSA getting around the Stub Area problem of not being able to import external addresses. It visualizes the following activities: the ASBR imports external addresses with a type 7 LSA, the ABR converts a type 7 LSA to type 5 and floods it to other areas, the ABR acts as an “ASBR” for other areas. The ABR’s do not take type 5 LSA’s and then convert to type 7 LSA’s for the area.