The suggested answer is B.
To passively receive traffic that passes through the appliance with Cisco FTD software, you need to configure the interface in 'passive' mode. In passive mode, the device operates as an Intrusion Detection System (IDS), where it monitors the traffic without being in the data path itself. It receives copies of the traffic, often through mechanisms like port mirroring (SPAN), enabling it to detect and analyze traffic without interfering with the actual data flow.