For Ethernet-to-Ethernet routers, such as the Cisco 831 behind a cable modem or DSL bridge, a traffic shaper is configured. This is required since the output 10-Mbps interface will not be congested. Which two statements are true?（）

• A、The parent policy-map shapes and the child policy-map queues.
• B、The mean-rate and burst-size must always be the same value.
• C、This will not work without a Dialer interface configured.
• D、The shaper provides congestion feedback.