__________ maintenance diagnoses and fixes errors in an operational system.

• A. Corrective
• B. Adaptive
• C. Perfective
• D. Preventive

Answer: (A)

Focusing on the maintenance type that is used when faults appear in an already running system, this is corrective maintenance. It involves diagnosing the fault, identifying the root cause, and applying a fix so the system returns to its expected operation. In practice, when a bug or failure is detected during operation, technicians troubleshoot, patch software, or replace defective components to restore normal function. This is different from preventive maintenance, which aims to reduce the chance of future faults through planned tasks; adaptive maintenance, which updates the system to work with changes in the environment or requirements; and perfective maintenance, which improves performance, reliability, or maintainability even when no fault exists. So, diagnosing and repairing errors in an operational system is corrective maintenance.