Which of the following events or processes in the 1840s or 1850s most directly contributed to the "irritations" that jefferson warned about in the letter above?

a. the acquisition of new territory in the west and the u. s. victory in the mexican-american war
b. the growth of violent nativist movements aimed at limiting immigrants’ influence and power
c. the movement of african americans and asians to the west
d. the increased settlement in areas forcibly taken from american indians