In which state is an interface placed if root-protect is enabled and a superior BPDU is received?

A.
root

B.
blocking

C.
forwarding

D.
alternate

Explanation:
Superior BPDU of STP
A superior BPDU is one that has a lower Bridge ID. An inferior BPDU would have a higher Bridge ID. This can’t be judged on a single BPDU basis. It’s only in comparison that one can be considered superior or inferior. Receiving a superior BPDU typically means that a switch received a BPDU with a lower Bridge ID than the Bridge ID of the currently elected root bridge.

If a switch receives an inferior BPDU, nothing changes. Receiving a superior BPDU will kick off a reconvergence of the STP topology.