The MAC protocol in the IEEE $802\mathrm{.}15\mathrm{.}4$ standard has two classes of physical devices, FFD and RFD$.$ A router in the network is an FFD device which

Group of answer choices

non of the above

has full functionality to communicate with its parent node

has reduced functionality to communicate with other FFD devices.

has full functionality responsible for network establishment and control

has full functionality to communicate with routers and RFDs$.$