Why is maintaining metal contact between the fuel nozzle and the fuel tank important?

Maintaining metal contact between the fuel nozzle and the fuel tank is crucial primarily to prevent the generation of static electricity, which can create sparks. When fueling, if the nozzle is not in direct contact with the tank, friction can lead to the buildup of static charges. These static charges can discharge as sparks, which pose a significant risk of igniting the fuel vapors present in the area, leading to potentially dangerous situations including fires or explosions. This safety measure is particularly important in environments where flammable liquids are present, ensuring that fueling procedures are as safe as possible.

While the other options highlight important aspects of the fueling process, they do not address the critical safety issue associated with static electricity.