A port in a redundant topology is currently in the blocking state and is not receiving BPDUs. To ensure that this
port does not erroneously transition to the forwarding state, which command should be configured?

A.
Switch(config)#spanning-tree lopguard default

B.
Switch(config)#Spanning-tree bpdufilter

C.
Switch(config)#udld aggressive

D.
Switch(config)#spanning-tree bpduguard