With unmanaged CE routers, at which point in the service provider network is the QoS trust boundary, and what is require

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With unmanaged CE routers, at which point in the service provider network is the QoS trust boundary, and what is required at the trust boundary?

A. between the CE and PE router and mapping of the customer traffic classes into the service provider traffic classes at the PE router ingress
B. between the CE and PE router and trusting the QoS markings from the CE router and applying the required QoS mechanisms based on the customer QoS markings
C. between the PE and the P router and mapping of the customer traffic classes into the service provider traffic classes at the P router ingress
D. between the PE and P router and trusting the QoS markings from the CE router and applying the required QoS mechanisms based on the customer QoS markings
E. between the customer network and the CE router ingress and applying the required egress QoS policy on the CE router