Answer:
c. Lack of food sources
Step-by-step explanation:
The groundwater has been used more and more around the world. There are large reserves of it, but in the past few decades the groundwater reserves have constantly been going down. The main reason for this is the lack of food sources. Because the global population is constantly on the rise, more and more food is needed, and in order to produce it, more and more farmlands are created. The increased number of farmlands means that more water is needed for irrigation, thus the groundwater reserves are the ones that suffer the most.