Refer to the exhibit.
policy-map WAN class class_A shape average 512000 32000 ! interface serial 4/0 service-policy input WAN
Which configuration error prevents this traffic-shaping policy from working?

A.	The WAN interface is starting to drop packets because no queuing mechanism is implemented.
B.	Traffic-shaping policies are applied only in the outbound direction.
C.	The class_A configuration shape peak is used to maximize the serial interface performances.
D.	The service-policy command is applied only on logical or channeled interfaces.