The correct answer is "D: Reliable".
Each political party has constantly updated its procedures in order to make more transparent elections among its representatives. In the case of the Presidency, internal elections are run by each party to select the individual who will represent the party at the presidential election. These candidates are obliged to publish the amount of money they have raised.
As for ballots, electronic methods have reduced the number of invalid votes. As the more traditional methods such as pieces of paper made it easier for voters to commit mistakes and have their votes nullified.