What aspect of LPG's expansion rate signifies a greater hazard?

The selection indicating that LPG presents a greater fire hazard compared to vapor leaks is significant due to the behavior of LPG when released into the air. LPG, or liquefied petroleum gas, when it vaporizes, can create a mixture with air that is more flammable than many other fuels, thereby increasing the risk of ignition and fire.

The expansion rate of LPG is important because when it changes from liquid to gas, it expands significantly, resulting in a larger volume of potentially explosive vapor. If there is a leak, the vapors can accumulate in low-lying areas and create an explosive atmosphere. This characteristic, coupled with the high density and low visibility of LPG gas, can make detection and proper venting difficult, exacerbating the fire hazard.

While other options touch on relevant details about LPG (like its combustion temperature and ignition energy), the key aspect showcasing the hazard in this context is the significant threat posed by vapor leaks. This factor elevates the risk significantly if proper precautions are not taken, thereby highlighting the importance of safety measures when dealing with LPG systems.