Which Configuration Tells a Switch Port to Send Cisco Discovery

Which configuration tells a switch port to send Cisco Discovery Protocol packets that configure an attached Cisco IP phone to trust tagged traffic that is received from a device that is connected to the access port on the Cisco IP phone?

A) Router# configure terminal Router(config) # interface gigabitethernet 5/1 Router(config-if) # platform qos trust extend
B) Router(config-if) # platform qos trust extend cos 3
C) Router(config-if) # platform qos trust extend cos 5
D) Router(config-if) # platform qos extend trust