Which technology is an example of the need for a designer to clearly define features and designedperformance when designing advanced WAN services with a service provider？（）

• A、 FHRP to remote branches.
• B、 Layer 3 MPLS VPNs routing.
• C、 Control protocols （for example Spanning Tree Protocol） for a Layer 3 MPLS service.
• D、 Intrusion prevention， QoS， and stateful firewall support network wide.