Final answer:
John D. Rockefeller gained a significant stake in Standard Oil through a stock swap, using a trust to legally control and consolidate the oil industry, eventually achieving near-total control over the nation's oil refineries.
Step-by-step explanation:
American industrialist John D. Rockefeller utilized the trust structure to amass great control over the oil industry through his corporation, Standard Oil. By having a group of trustees own the majority of shares in various oil companies, Rockefeller was able to make decisions for these companies and secure large profits, which was legal at the time. This allowed for horizontal integration, where he merged or drove out his competition, ultimately leading to near-total control in the oil refining industry. Rockefeller's Standard Oil Trust came to control 90 percent of the nation's oil refineries and his influence spanned even to the transportation sector through vertical integration, where he acquired interests in businesses across the entire supply chain.