Which Cisco IOS traffic-shaping mechanism statement is true？ （）

A. class-based policing is configured using the Modular QoS command-line （MQC）
B. only the Frame Relay traffic-shaping （FRTS） mechanism can interact with a Frame Relay network， adapting to indications of Layer2 congestion in the WAN links
C. Distributed Traffic Shaping （DTS） is configured with the police command under the policy map configuration
D. both Frame Relay traffic shaping （FRTS） and virtual IP （VIP）-based Distributed Traffic Shaping （DTS） have the ability to mark traffic