What are the three categories of maintenance?

The three categories of maintenance recognized in the Navy's Maintenance & Material Management (3-M) system are preventive, corrective, and operational maintenance.

Preventive maintenance involves routine tasks performed to preserve equipment functionality and prevent failures before they occur. This category focuses on regular inspections, servicing, and minor adjustments to ensure that systems operate effectively and efficiently.

Corrective maintenance refers to the repairs made after equipment fails or malfunctions. It addresses the immediate issues that arise and restores the equipment to a satisfactory condition.

Operational maintenance encompasses actions necessary to maintain systems during regular operations. This could include checks and adjustments that ensure equipment remains operational during day-to-day activities.

Each of these categories plays a vital role in ensuring the reliability and efficiency of Navy systems and equipment, making option D the correct choice.