Answer:
D. Contamination of groundwater
Hydraulic fracturing is also called as fracking. It is a drilling process which is used for the excavation of oil and natural gas from the shale rock beneath the earth crust. In this the hydraulic pressure is used by using the chemicals mixed with sand and water. This water is injected forcefully into the rocks. The gas or oil comes out from the gaps created. This process can contaminate the groundwater reservoir.