You are working with a client to classify the different types of application traffic they will have on their network and to assign a QoS value to each traffic flow. The client has identified the following applications: Internet traffic, Oracle, network-based backups, AOL Instant Messenger, IP routing, voice, and voice signaling. Given these types of applications, how many different classes will need to be configured in QoS?（）

A. 8
B. 6
C. 9
D. 5