How does DiffServ deliver QoS across the network?
A.
 DiffServ classifies and marks traffic at each node in the network.
B.
 When using DiffServ, the network tries to deliver a particular kind of service that is based on the 
QoS that is specified by each packet.
C.
 DiffServ tries to deliver a particular level of service on a per-flow basis across the network.
D.
 DiffServ delivers a particular kind of service based on either a flow-based behavior or a per-hop 
behavior, depending on how the traffic was marked and classified at ingress.