Which of the following terms refers to a prolonged loss of power?

A spike is a sudden, extremely brief overvoltage event that can damage sensitive hardware but involves excess voltage, not a loss of power.

A brownout is a partial, sustained reduction in voltage below the normal operating level - power is still present but degraded, not completely absent.

A surge is a temporary increase in voltage that lasts longer than a spike but still represents excess electrical energy rather than a loss of power.

A blackout refers to a total interruption of electrical power that persists for an extended duration, typically caused by grid failures, natural disasters, or major equipment faults. It is the most severe category of power event and is the term used in IT continuity planning to describe scenarios requiring UPS systems or backup generators to sustain operations.