What additional requirement is stipulated at each underground oil storage station besides fire extinguishers?

The correct answer indicates that in addition to fire extinguishers, each underground oil storage station is required to have 240 pounds of rock dust. This requirement is critical for safety, as rock dust can be used to suppress fires and explosions in the context of combustible materials like oil and hydrocarbons. Rock dust works by inhibiting the combustion process, reducing the intensity of any potential fires and minimizing the spread of flames.

This specific requirement ensures that operators have an effective means of dealing with fire hazards that may arise in an environment where flammable substances are stored. Having a sufficient quantity of rock dust on hand contributes to a proactive safety strategy, aimed at maintaining a safe working environment.

In contrast, while options suggesting sand or additional fire hoses may seem like plausible safety measures, they do not meet the established regulations in terms of quantity and effectiveness for suppressing fires in underground oil storage scenarios. Additionally, claiming there is no additional requirement would overlook the regulatory standards necessary for ensuring site safety.