A network security engineer must replace a faulty Cisco FTD device in a high availability pair. Which action must be taken while replacing the faulty unit?
A. Ensure that the faulty Cisco FTD device remains registered to the Cisco FMC
B. Shut down the active Cisco FTD device before powering up the replacement unit
C. Shut down the Cisco FMC before powering up the replacement unit
D. Unregister the faulty Cisco FTD device from the Cisco FMC
