Refer to the exhibit.  Which statement is true when voice traffic is forwarded on the same VLAN  used by the data traffic？ （）

• A、The voice traffic cannot be forwarded to the distribution layer.
• B、The voice traffic cannot use 802.1p priority tagging.
• C、Port security cannot be enabled on the switch that is attached to the IP phone.
• D、Quality of service cannot be applied for the voice traffic.