You want to mitigate failures that are caused by STP loops that occur before UDLD detects the failure or that are caused by a device that is no longer sendingBP...

You want to mitigate failures that are caused by STP loops that occur before UDLD detects the failure or that are caused by a device that is no longer sendingBPDUs. Which mechanism do you use along with UDLD?

A. BPDU guard B. root guard C. loop guard D. BPDU filtering