The ideas expressed in the passage above most directly led to political controversies in the 1870s and 1880s over a. new definitions of citizenship. b. the expansion of slavery into western territories. c. the proper balance between liberty and order. d. a sense of American cultural superiority.

Option: a. new definitions of citizenship

Explanation:

The Naturalization Act of 1870 promoted equality for the African Americans but kept racial differences and denied naturalization rights (citizenship) to Asian immigrants.  The law designed to end the open immigration policy introduced by the Founding Fathers.