Final answer:
Many U.S. citizens supported immigration restrictions in the early 20th century because they believed immigrants took jobs from U.S. citizens, fueled by nativist sentiment and concerns over economic security and cultural cohesion.
Step-by-step explanation:
At the turn of the 20th century, many U.S. citizens supported restrictions on immigration for several reasons. A prominent belief was that immigrants competed with U.S. citizens for jobs, which is reflected in option C. This view was compounded by nativism, a preference for native-born inhabitants over newcomers, particularly those coming from southern and eastern European countries, backed by claims of protecting the country's moral fiber. The backlash against immigrants led to organizations like the American Protective Association advocating for restrictive laws such as the Chinese Exclusion Act and the National Origins Act, aiming to curb immigration and protect job opportunities for U.S. natives.
Furthermore, immigrants were often blamed for economic difficulties and for being a threat to cultural cohesion, which fueled the push for restrictive immigration policies. The belief was that immigrants threatened the economic security and cultural norms of native-born Americans. This sentiment fostered a politically charged environment encouraging restrictive legislation aimed at preserving jobs and resources for citizens.
As a result, immigrants faced discrimination and were erroneously blamed for complex socioeconomic issues, making them targets of prejudice and legislative acts aimed at reducing their presence in American society.