What should be used to cover all fuel during operations?

Using foam to cover all fuel during operations is the most effective choice because foam is specifically designed to extinguish flammable liquids and create a barrier between the fuel and oxygen, thereby preventing the fire from spreading. Foam works by forming a thick blanket that smothers the fuel and suppresses the vapor release that can lead to ignition.

In contrast, while water can sometimes be used to cool a fire, it can also spread flammable liquids, making the situation worse. Sand may help to smother flames to some extent, but it does not provide the same level of control or suppression as foam. Absorbent materials can help soak up spills, but they do not extinguish fires and might not be effective against flammable vapors. Ultimately, foam is the most suitable agent for efficiently covering fuel and preventing fire hazards during operations.