Which statement is NOT a key QoS recommended requirement for voice bearer traffic?（）

• A、Voice traffic should be marked to DSCP EF per the QoS baseline and RFC3246.
• B、Voice traffic loss should be no more than 3%.
• C、One-way latency （mouth-to-ear） should be less than 150 msec.
• D、Average one way jitter should be targeted to less than 30 msec.
• E、21-320 Kbps of guaranteed priority bandwidth is required per call depending on sample rate，codec，and  layer 2 overhead.