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.