Lets take a look in each statement:
monitoring campaigns to ensure everything is legal - False - It is The Federal Election Commission (FEC) administers federal campaign finance laws;
monitoring polling stations to ensure ballots are long form - True - One of the responsibilities of the election official is to provide ballots (device used to cast votes);
approving ballots for voters to use - False - The State has the authority to regulate the approval of the ballots;
monitoring polls to ensure everything is legal - True - They are responsible for the proper and orderly voting at polling stations;
reporting back to party officials with any issue or discrepancy they may have found at the polls - False - It does not correspond to the duties of the election official.
Which gives us B and D correct.