To ensure continuous operation despite component failure, the system uses a mechanism where a backup component automatically takes over.

• A. Redundancy
• B. Fault Tolerance
• C. High Availability
• D. Failover

Answer: (D)

The essential idea here is automatic switching to a backup component when the primary one fails. That automatic handoff is called failover. It keeps services running by detecting a failure and redirecting to the standby system without human intervention. Redundancy means having spare components available, which makes failover possible, but redundancy alone isn’t describing the act of switching. Fault tolerance is a broader capability to operate despite faults, often using redundancy and error handling, not just the automatic takeover. High availability is the goal of keeping systems up with minimal downtime, typically achieved through failover among other techniques. So the mechanism described—the automatic transfer to a backup component—best matches failover.