How did john d. rockefeller horizontally integrate his monopoly in 1880?

a. he purchased iron mines around the country to add to his business.
b. he created a trust that controlled ninety percent of the nation's oil refineries.
c. he created a trust that controlled oil wells, refineries, and distribution networks.
d. he purchased coal plants around the country to add to his business.

(100 points) project: progressive era research your topic and write at least seven hundred words to discuss one of the following topics. a. evaluate the impact of progressive era reforms. b. evaluate the impact of progressive reform leaders such as susan b. anthony or robert lafollette. c. evaluate the impact of third parties and their candidates such as h. ross perot and george wallace on america. note: as with any research you do, evaluate the validity of your source: a. who is the author? b. is the author an authority on the subject? c. how does the author use language? d. what sources appear in the author's work? e. from what you know or have learned about the author, is the presentation inappropriately biased?