All _________ equipment and components that are buried or mounded shall be coated or protected and maintained to minimize corrosion.

The correct response focuses on metallic equipment and components because they are particularly susceptible to corrosion when exposed to soil or moisture. Metallic materials like steel and iron can easily corrode if not properly protected, which can lead to leaks or failure of equipment in a propane system.

Coating or protecting these metallic components—through methods like paint, galvanization, or using corrosion-resistant alloys—is essential for ensuring their longevity and safe operation. Corrosion not only affects the integrity of the materials but can also pose significant safety risks due to potential leaks, which can lead to hazardous situations in a propane system.

In contrast, plastic and fiberglass materials typically resist corrosion, as they do not suffer from the same chemical reactions with moist soil as metals do. Wooden components can also degrade but do not generally present the same risks as metallic components in the context of corrosion within propane systems. Thus, the emphasis on maintaining metallic equipment is crucial in mitigating corrosion-related issues.