Refer to the exhibit. OSPF is configured on all routers in the network. On the basis of the show ip ospf n eighbor output, what prevents R1 from establishing a full adjacency with R2? （）

• A、Router R1 will only establish full adjacency with the DR and BDR on broadcast multi- access networks.
• B、Router R2 has been elected as a DR for the broadcast multiaccess  network in OSPF area 1.
• C、Routers R1 and R2 are configured as stub routers for OSPF area 1 and OSPF area 2.
• D、Router R1 and R2 are configured for a virtual link between OSPF area 1 and OSPF area 2.
• E、The Hello parameters on routers R1 and R2 do not m atch.