By 1878, the Standard Oil Company, owned by John D. Rockefeller, had bought out most of its business rivals and controlled 90% of the petro-leum refineries in the United States. Which of the following was a likely effect of Standard Oil's business practices?
Explanation
Choice "The company increased oil prices" is the most likely effect. By eliminating its competitors, Standard Oil controlled most of the production of oil and could artificially drive up prices.