下列说法中（）是正确的

• A、C-Plane Latency shows the idle to active transition time the end user may experience to setup a service./控制面时延反映了用户为建立业务而从空闲模式到激活模式经历的时间
• B、U-Plane shows the PING round trip time in the end to end communication/用户面时延反映了端到端通信中PING包的环回时间
• C、Peak DL Cell Throughput shows the average  throughput the cell can reach in downlink, on the application layer./小区下行峰值吞吐量反映了该小区下行方向可以达到的应用层平均吞吐量
• D、Attach Time shows the connection time for an end user to attach to the network, during which the activation of a default bearer is performed./Attach时间反映了用户Attach到网络所需的连接时间，其间将激活默认承载