An engineer must automatically copy the IP Prec/DiffServ PHB marking to the EXP bits of the imposed MPLS label on the ingress PE, as well as the MPLS EXP bits to the IP Prec/DiffServ of the egress PE. Which MPLS QoS model is suitable for this requirement?
A. pipe model
B. short-pipe model
C. uniform model
D. uniform pipe model
