Which type of transport is primarily associated with the potential for significant vapor releases during leaks?

The correct choice focuses on low-pressure rail cars, which are often designed to transport hazardous liquids and gases that can be subject to vapor release during leaks. These rail cars typically operate at lower internal pressures, which means that while they can transport significant quantities of materials, they can also allow for the release of vapors if leaks occur. The low pressure can lead to a greater potential for vaporization of the cargo, particularly if environmental conditions change, causing the liquid to vaporize more readily.

While high-pressure cargo ships, road tanker trucks, and air freight containers can also carry hazardous materials, they are generally designed to contain their contents under higher pressure, which reduces the likelihood of vapor release in the event of a leak. High-pressure systems are typically more resilient to releases and limit vaporization, whereas low-pressure systems do not offer the same level of containment and can release larger volumes of vapor more easily.