How does groundwater become polluted?
a.

pollutants mixed with water pass through permeable layers above the aquifer.
b.

factories dump their waste directly into aquifers.
c.

refuse infiltrates the water table when garbage is dumped.
d.

all of the above

a. Pollutants mixed with water pass through permeable layers above the aquifer.

Groundwater is a source of water which gets deposited under the Earth sub layers. Water gets deposited through pores or fractures present in the soil, sand and rocks obtain from precipitation, river, lakes, ponds and other sources. The reserve source of water in the ground level is called aquifer. As water enters in the ground through pores and fractures in the soil and rocks. Pollutants may also enter along with this water and through permeable layers of soil these pollutants gets mixed with ground water. Hence, contaminates the aquifer.

allowed for the prediction of the properties of missing elements.