Which Cisco Catalyst feature automatically disables the port in an operational PortFast upon
receipt of a BPDU?

A.
BackboneFast

B.
UplinkFast

C.
Root Guard

D.
BPDU Guard

E.
BPDU Filter

Explanation:
We only enable PortFast feature on access ports (ports connected to end stations). But if
someone does not know he can accidentally plug that port to another switch and a loop may occur
when BPDUs are being transmitted and received on these ports.
With BPDU Guard, when a PortFast receives a BPDU, it will be shut down to prevent a loop.