Which of the following statement about QoS in DiffServ mode is false?

Which of the following statement about QoS in DiffServ mode is false?

A. The parameter field in the IP packet header informs devices on the network of the QoS requirements of the application. B. Every device on the packet transmission paths can learn the service request types by analyzing the IP packet header. C. Before sending packets, the application program needs to confirm that the network has reserved resources for packet transmission. D. DiffServ is a QoS solution based on packets.