Final answer:
Nativists in the nineteenth century United States were motivated by prejudice against immigrants, fearing they threatened the American way of life and would take jobs and remain loyal to foreign powers. The correct option is B.
Step-by-step explanation:
The motivation of the nativists in the United States during the nineteenth Century was B) Prejudice against immigrants. Nativists held the belief that the presence of immigrants threatened the cultural, political, and economic life of native-born Americans.
They feared that immigrants would take jobs from Americans, bring unfamiliar and undesirable customs, and exhibit loyalty to foreign entities, such as the Catholic Pope, rather than American democratic ideals. The correct option is B.