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.