Which commands are required for proper functioning of OSPF in this case?

Ten routers, R1 through R10, connect in a partial mesh over Frame Relay. For the mesh, R1
and R2 have PVCs connected to all other routers, but Routers R3 through
R10 act as branch routers, with only two PVCs–one to R1 and one to R2. The routers use IP
subnet 10.1.1.0/24, with addresses 10.1.1.1, 10.1.1.2, and so on, through 10.1.1.10,
respectively. The routers all use Inverse ARP to learn Frame Relay mapping information. All
routers use a multipoint subinterface with network type point-tomultipoint nonbroadcast. A
co-worker’s implementation plan lists lots of configuration commands related to this design.
The design states that all hosts should be able to ping all other hosts. Which commands are
required for proper functioning of OSPF in this case? (Choose two.)

A.
frame-relay map commands on R3–R10 referencing the other routers in this group.

B.
Nine OSPF neighbor commands on each router.

C.
Nine OSPF neighbor commands on R1 and R2, with only two such commands on R3–
R10.

D.
R1 and R2 with ip ospf priority 1 commands to ensure they become DR and BDR.

E.
R3–R10 with ip ospf priority 0 commands to ensure they do not become DR or BDR.

Explanation:
For routers to use their OSPF routes in a multipoint design, each router
needs mapping to each other router in the Frame Relay subnet. In this case, R3–R10
all need frame-relay map commands to define the mapping to other routers with

which they do not have a PVC. This network type requires static definition of neighbors,
but the neighbor relationships match the PVC topology, so R3–R10 need only
two neighbor commands. This OSPF network type does not use a DR, so the ip ospf
priority commands have no effect and would be unnecessary.