referring to the years 1920 to 1940 on the graph, which of the following was a catalyst for the upward trend in the presidential popular vote as a percent of the population in that period? choose 1 answer: choose 1 answer: (choice a) a banning poll taxes used to prevent african americans from voting (choice b) b reducing the voting age for elections (choice c) c giving women the right to vote (choice d) d changing the method by which us senators were elected