An engineer must configure high availability for the Cisco Firepower devices. The current network topology does not allow for two devices to pass traffic concurrently. How must the devices be…

Active/active mode (clustering) requires both devices to concurrently pass traffic, which directly contradicts the problem statement that the network topology 'does not allow for two devices to pass traffic concurrently'.

EtherChannel is a link aggregation technology for redundancy and increased bandwidth, not a high availability mode that addresses the concurrent traffic limitation between two firewall devices.

Active/passive (failover) mode for Cisco Firepower ensures that only one device processes traffic at any given moment, with the other remaining as a standby. This implementation is ideal for network topologies that do not support or are not configured to handle concurrent traffic flows from multiple active firewall devices.

'Cluster interface mode' is not a standard high availability mode for Cisco Firepower; the common modes are active/active (clustering) and active/passive (failover).