One Explanation Given by the Text for the Decline in U.S.voter

 One explanation given by the text for the decline in U.S.voter participation in presidential elections after 1900 is that 

A)  parties began functioning to mobilize mass voter turnout. 
B)  fewer citizens were directly affected by the outcome of presidential elections. 
C)  other forms of political participation became more accessible to citizens. 
D)  election fraud was rampant during the nineteenth century. 
E)  the Republican Party began to attempt to mobilize individuals who were least likely to vote.