Question

liquid leaking from a landfill is a big problem because it can contaminate which of these? the mantle groundwater sewage the atmosphere

Explanation:

Landfill liquid leakage can seep into the ground and contaminate groundwater. The mantle is too deep and not directly affected by landfill liquid. Sewage is waste water that is usually treated and not the target of landfill liquid contamination in this context. While landfill gas can affect the atmosphere, the question is about liquid leakage which mainly impacts groundwater.

Answer:

groundwater