A、They are originated by Area Border Router and are sent into a single area to advertise an Autonomous System Border Router.

B、They are originat ed by Area Border Routers and are sent into a single area to advertise destinations outside that area.

C、They are originated by the DR on every multi - access network. They include all attached routers including the DR itself.

D、They are originated by  every router in the OPSF network. They include all routers on the link, interfaces, the cost of the link, and any known neighbor on the link.