Which statement from the options provided best summarizes the main point regarding the factors influencing Western settlement?
a) Irrigation made ranching and homesteading possible in areas where water was scarce.
b) Barbed wire enabled cattle ranchers to raise huge herds on ample grazing land without worrying about them wandering off.
c) Although Winchester rifles and Colt revolvers were often credited with "winning the West," technological and social advances were far more significant factors in Western settlement.
d) The railroad brought settlers, supplies, jobs, and mail, and made the concept of a single, undivided, universally accessible America a reality.
