Final answer:
John D. Rockefeller established a virtual monopoly in the oil industry through horizontal integration and creation of trusts, as well as employing vertical integration to control all aspects of oil production.
Step-by-step explanation:
John D. Rockefeller utilized horizontal integration as a form of expansion to create a virtual monopoly in the oil production industry during the late 19th century. By merging with other oil companies or driving his competition out of the market through underpricing and making secret deals with suppliers and railroads, Rockefeller's Standard Oil Company eventually controlled a staggering percentage of the oil refineries.
His strategy included the creation of trusts to manage and dominate the industry, allowing him to manipulate oil prices once he held significant market power. Additionally, Rockefeller's Standard Oil began to practice vertical integration, controlling every aspect of a product's lifecycle, to further consolidate his control over the industry.