Idk d it might be d i might be wrong
The answer is b)<span> groundwater was overpumped
As population in Mexico City and the </span><span>San Joaquin Valley skyrocketed, the demand for water also increased.
Mexico City was once the most populated city on earth and that created a lot of burden on the cities infrastructure including the water supply.
The groundwater was over pumped leading to huge problems for millions of people.</span>
It would be difficult for the United States for two reasons, the fact that none of the land was mapped other than the areas that previous voyagers had gone through, and the natural landscape of the area, and last, Native American Hostility.
Three examples: When pioneers would voyage to the west, there would often be encounters were they would be attacked by animals that had not been seen before, bears, sneaks, different wolves, and many more. They barely knew the natural resources of the area, such as food, etc.
The next example, no mapping, would be difficult because for the most part, they had no sense of navigation except for the few maps that had been made, even then, would be difficult to navigate.
Native Americans did not appreciate the pioneers coming into the land they considered their own, they resembled hostility and would even kill the civilians that would travel through the land, or capture them.
Hope this helps!! <3
The 3rd one is the correct answer
Although the United States was actively involved in World War I for only nineteen months, from April 1917 to November 1918, the mobilization of the economy was extraordinary. ... Over four millionAmericans served in the armed forces, and the U.S. economyturned out a vast supply of raw materials and munitions.