Final answer:
Many Americans feared immigration primarily because they believed that immigrants would work for low wages, leading to job competition. They also harbored nativist sentiments, fearing cultural change and unwillingness to assimilate to American values, which led to legislative actions against certain groups.
Step-by-step explanation:
Many Americans feared immigration because they believed that immigrants would work for low wages, which is reflected in option A. This fear was rooted in several concerns about the economic and cultural impacts of immigration. Foremost among these concerns was fear of competition from foreign workers who would accept lower wages than the native population, thereby threatening job security and wage levels for American workers.
Additionally, this era saw the rise of nativist sentiments that targeted certain demographic groups. Nativists opposed the migration of nonwhites, non-Protestants, Jews, and so-called 'new' immigrants from Central and Southern Europe and Asia. The tension was not solely economic; it also pertained to worries that immigrants would not assimilate into or accept American values. White Americans, in particular, were hostile to Asian immigrants, led to several legislative acts aimed at restricting immigration and naturalization from Asia.
During this period, an increase in the Roman Catholic population due to immigration from Ireland and Germany led to cultural changes and social tensions as well. Therefore, while the economic fear of immigrants taking jobs by working for lower wages was a significant factor, it was accompanied by broader cultural and racial anxieties.