Refer to the exhibit. What is the effect on the trust boundary of configuring the command mls qos trust cos on the switch port that is connected to the IP phone？（）
- AEffectively the trust boundary has been moved to the IP phone
- BThe host is now establishing the CoS value and has effectively become the trust boundary
- CThe switch is rewriting packets it receives from the IP phone and determining the CoS value
- DThe switch will no longer tag incoming voice packets and will trust the distribution layer switch to set the CoS
- ERTP will be used to negotiate a CoS value based upon bandwidth utilization on the link