Answer:
Groundwater
Explanation:
The factories mostly need large quantities of water to carry out their production precesses, however, as well as they need natural recources for their operation, they also dispose of them and a large part of the environmental contamination is due to the release of substances emitted by these. It´s very easy for toxic waste to contaminate rivers, lakes and aceans. Groundwater on the other hand is more complicated to contaminate because it´s found in aquifers below the surface of the arth, making by these factories to reach these places; althouh not impossible.