Which statement about the DiffServ model is true?

Which statement about the DiffServ model is true?

A.
DiffServ provides traffic management using QoS classifications.

B.
DiffServ specifies a mechanism for classifying and managing network traffic and providing QoS
on modern IP networks.

C.
DiffServ is based on building a virtual circuit in the Internet using the bandwidth reservation
technique.

D.
DiffServ is a way to provide the assurance of sufficiently low delay and packet loss for certain
types of applications or traffic.