You have a Level 1-only router （Router A） in IS-IS area 49.0001. How does Router A learn how to get to IP prefixed in other areas？（）

• A、Router A must have a Level 2 adjacency with the Level 1/Level 2 router in area 49.0001.
• B、The Level 1/Level 2 router in area 49.0001 sets the "attached" bit in the Level 2 LSP it floods into area 49.0001.
• C、The Level 1/Level 2 router in area 49.0001 sets the "attached" bit in the Level 1 link-state PDU （LSP） it floods into area 49.0001.
• D、The Level 1/Level 2 router in area 49.0001 advertises these prefixed into area 49.0001 using a Level 2 LSP it floods into the area.