Which three statements about end-to-end delay are true？（）
- AEnd-to-end delay is the sum of propagation delays，processing delays，serialization delays，and queuing delays.
- BCoast-to-coast end-to-end delay over an optical link is about 20 ms.
- CProcessing delay depends on various factors，which include CPU speed，CPU utilization，IP switching mode， and router architecture.
- DPropagation and serialization delays are related to the media.
- EPropagation delay is the time it takes to transmit a packet and is measured in bits-per-second （bps）.
- FSerialization delay is the time it takes for a router to take the packet from an input interface and put it into the output queue of the output interface.