If I was an environmentalist giving a speech about environmental concerns due to population growth in the western United States, the most important detail I would include is option C: depletion of freshwater due to city growth.
Water is not used efficiently, so it would be a really serious issue to deal with, if a population growth takes place and result in the depletion of water.
For instance, the scarcity of fresh water for agriculture may emerge as a more immediate problem. Almost one-fifth of the world’s population lives in areas where water is physically scarce, so that a rapid and increasingly population growth has given way to an enormous expansion of agriculture, which is now estimated to account for 92 percent of the world’s use of fresh water.
