The correct answer is A) Secret ballots.
Secret ballots were part of a drastic change in voting in American society. Before the Progressive era (late 19th century) political parties were in charge of printing their own ballots. This means they had the opportunity to control who was on the ballot, often including just people from there political party.
With the secret ballot, individuals would have all nominees running for a position. Along with this, privacy of what/who an individual voted for was a significant part of the secret ballot. Implementing this system was a goal of Progressives, as they thought it would result in less corruption on local, state, and federal levels.