Final answer:
Windmills were essential for irrigation on the Great Plains, aiding homesteaders to establish farms, supported by policies like the Homestead Act and the expansion of railroads.
Step-by-step explanation:
Among the options given, the windmills to pump water for irrigation were a crucial technology that helped many homesteaders establish farms on the Great Plains during the 1800s. These pioneering homesteaders faced challenging climate conditions, with typically low rainfall and harsh temperatures making crop cultivation difficult. While dry-farming techniques were common, some farmers began to employ windmill technology to draw water, making it feasible to farm on arid land.
However, the Homestead Act of 1862 and technological advancements like the steel plow improved farming success, and the expansion of the railroad made transport of crops and farming supplies more accessible. Ultimately, these developments led to a significant population shift and contributed to the growth of industry and cities in the West.