How did direct primary change the political system?

A direct primary, which is now used in some form in all U.S. states, functions as a preliminary election whereby voters decide their party’s candidates. In an indirect primary, voters elect delegates who choose the party’s candidates at a nominating convention.

Explanation:

d. it gave farmers a way to organize for more political power

if i am correct the answer is going to be a) the federal program of reconstruction ended.