According to the best practices, in a service provider network, which statement is true as related to the QoS policy that should be implemented on the inbound provider (P) to provider (P) router link?

A.
Traffic policing should be implemented to rate-limit the ingress traffic into the P router.

B.
Because traffic should have already been policed and marked on the upstream ingress PE router, no input QoS policy is needed on the P to P link.

C.
Class-based marking should be implemented because it will be needed for the class-based queuing that will be used on the P router output.

D.
In the DiffServ model, all ingress and egress QoS processing are done at the network edge (for example, PE router), so no input or output QoS policy will be needed on the P to P link.