Which statement best describes OSPF external LSAs （type 5）？（）

• A、OSPF external LSAs are automatically flooded into all OSPF areas, unlike type 7 LSAs, which require that redistribution be configured.
• B、External LSAs (type 5) are automatically changed to type 1 LSAs at ASBRs.
• C、Type 5 LSAs are route summaries describing routes to networks outside the OSPF Autonomous System.
• D、External network LSAs (type 5) redistributed from other routing protocols into OSPF are not permitted to flood into a stub area