Which compound is designed to flow into difficult-to-reach areas, such as inside hood and trunk ledges?

Cavity wax is specifically formulated to penetrate and flow into hard-to-reach areas of a vehicle, such as inside hood and trunk ledges. Its design allows it to provide comprehensive coverage in these areas, which are often prone to moisture accumulation and corrosion. The wax adheres to surfaces and creates a protective barrier that prevents rust and deterioration, making it crucial for long-term vehicle maintenance and durability in challenging environments.

The other options serve different functions: sealers are typically used for adhesion or to create water-tight barriers; undercoating provides a protective layer to the underside of vehicles, guarding against road debris and moisture; and rust inhibitors are designed to prevent corrosion but may not have the flow characteristics needed to reach into complex voids and crevices.