Final answer:
John D. Rockefeller's Standard Oil Company became a monopoly by organizing independently operated oil companies under a trust, controlling the majority of the oil industry in the United States.a) A monopoly
Step-by-step explanation:
He became the richest man in the world though his company Standard Oil is a monopoly. John D. Rockefeller, the founder of Standard Oil, revolutionized US industry by organizing various independent oil companies into a trust. This allowed him to control the nation's oil industry, which led to the company's dominance as a monopoly. A monopoly is defined as the exclusive possession or control of the supply or trade in a commodity or service.
Rockefeller's Standard Oil Company utilized a business model that operated through a trust, with Rockefeller creating a holding company to control multiple companies by holding the majority of their stocks. This consolidation of power and authority under one entity essentially functioned as a monopoly, leading to significant challenges from state and federal bodies, eventually resulting in the dissolution of the company under anti-monopoly laws.