One method that was used to reform presidential campaign financing in the united states was to a. use public dollars to provide funding for candidates b. allow unlimited contributions from nonprofit groups c. encourage donations from foreign individuals d. deny candidates funding from political parties

The Campaign Financing was a method used by political sponsors candidates to get funds for a specific group of people and special interest, first of all, that campaign allowed limited donations and contributions to individuals to be part of the elections of the U.S senator, however, years later, that law was restricted because of some disclosures. I can say that correct option is letter d because at first the movement offer a portion to raise fund for political parties, but in 1867, prohibit political parties donations that were solicited to naval workers.

i believe we're not a republic so that is a hard question

the answer is b your welcome : )