Answer:
BPDU guard
Explanation:
BPDU stands for Bridge Protocol Data Unit. In order to prevent ports that are serving network hosts from being considered as best paths, BPDU guards should be enabled to block BPDUs. BPDU guards can be enabled or disabled depending on the function required. BPDU filters filters the inbound and outbound BPDU. BPDU filters are different from BPDU guards. So option (c) BPDU filter is wrong. Option (a) root guard is wrong as it is used for other purposes. Option (d) BPDU drop is wrong. As it is differenent from BPDU guard.
