The Transition in the Political Loyalties of African Americans Occurred

The transition in the political loyalties of African Americans occurred ______.

A) because the Democratic Party pushed extensive voting rights legislation through Congress during the New Deal
B) because Republicans blocked persistent Democratic efforts to restrict the voting rights of African Americans
C) very slowly and with very little effect because most African Americans lived in the South where they were disfranchised
D) through migration as African Americans moved north, and Democratic organizations registered them and ushered them to the polls