Which of the following is a telltale sign that may help spot potential underground hazards?

Water boxes serve as a significant indicator of potential underground hazards because they are often found above buried utilities such as water and sewer lines. These boxes typically house valves or meters for utility companies, and their presence points to the likelihood of infrastructure lying beneath the surface. Recognizing these signs is critical for operators to avoid accidental damage to underground utilities while excavating or operating heavy equipment.

On the other hand, excessive vegetation might suggest growth patterns associated with buried lines, but it is not as definitive as water boxes. Tool marks on the surface could indicate previous excavation or work done in the area, but they don't directly imply the presence of utilities or underground hazards. Therefore, while other indicators exist, water boxes are a clear signal to be aware of potential underground conflicts.