"Considering that a great part of the territories ... within the limits of the United States, is now occupied by savage tribes, who will hereafter be under the exclusive control of the Government of the United States, and whose incursions within the territory of Mexico would be prejudicial in the extreme, it is solemnly agreed that all such incursions shall be forcibly restrained by the Government of the United States whensoever this may be necessary; and ... they shall be punished by the said Government ... as if the same incursions were meditated or committed within its own territory, against its own citizens."—Treaty of Guadalupe Hidalgo, Article XI, 1848

"SEC. 2. And be it further enacted, That the right of way through the public lands be, and the same is hereby, granted to said company for the construction of said railroad and telegraph line; and the right, power, and authority is hereby given to said company to take from the public lands adjacent to the line of said road, earth, stone, timber, and other materials for the construction thereof; said right of way is granted to said railroad to the extent of two hundred feet in width on each side of said railroad where it may pass over the public lands ... The United States shall extinguish as rapidly as may be the Indian titles to all lands falling under the operation of this act and required for the said right of way and; grants hereinafter made."—Pacific Railway Act, 1862

Which of the following was a direct effect of westward expansion and the environmental transformations that occurred after the Mexican-American War? (1 point)

a
Creation of immigrant legislation to limit westward movement and disputes over shipping routes

b
Depletion of government coffers and default on the bonds issued to rail-building companies

c
Rapid reduction of populations in the East and lack of infrastructure to support them in the West

d
Settlement of immigrants working on the railroad and increased nativist sentiments