What does the root guard feature provide in a bridged network?

A.
it ensures that the bridge is elected as Root Bridge in the network.

B.
it enforces the root bridge placement in the network

C.
It ensures that BPDUs sent by the root bridge are forwarded in a timely manner.

D.
It ensures that all ports receiving BPDUs from the root bridge are in the forwarding state.

Explanation:
Root Guard—Enabled per port; ignores any received superior BPDUs to prevent a switch
connected to this port from becoming root. Upon receipt of superior BPDUs, this switch puts the
port in a loop-inconsistent state, ceasing forwarding and receiving frames until the superior BPDUs
cease.
The STP topology can be changed based on one of these unexpected and undesired switches
being added to the network. For instance, this newly added and unexpected switch might have the
lowest bridge ID and become the root. To prevent such problems, BPDU Guard and Root Guard
can be enabled on these access ports to monitor for incoming BPDUs.