A stream of voice packets transmitted over a WAN network encounters differing queuing delays. One router in the path used by the voice packets delays some of the packets for 4 ms while transmitting a large video file， but delays other packets only 2 ms. Another router delays some packets 5 ms， but transmits others in 2 ms. How would you best describe this type of problem？（）

• A、end-to-end delay
• B、interference from bulk data traffic
• C、processing delays
• D、serialization delays
• E、jitter