As an experienced network administrator, you are asked to troubleshoot a QoS problem. In which way might the Cisco NetFlow be helpful during the troubleshooting process?（）

• A、NetFlow can discover the protocols in use and automatically adjust QoS traffic classes to meet policy-map requirements.
• B、NetFlow records can be used to understand traffic profiles per class of service for data, voice, and video traffic.
• C、NetFlow can be configured to identify voice and video traffic flows and place them into a low-latency queue for expedited processing.
• D、NetFlow can report on the number of traffic matches for each class map in a configured QoS policy configuration.