Which is a benefit of implementing RFC 2827？（）

• A、Prevents DoS from legimate， non-hostile end systems
• B、Prevents disruption of "special services"， such as Mobile IP
• C、Defeats DoS Attacks which employ IPSource Address Spoofing
• D、Restricts directed broadcasts at the ingress router
• E、Allows DHCP or BOOTP packets to reach the relay agents asappropriate