Final answer:
Businesses that aimed to control the entire supply chain of an industry used vertical integration, as exemplified by John D. Rockefeller's approach to the oil refining industry. The correct option for such a strategy is B) vertical integration.
Step-by-step explanation:
The strategy used by businesses that aimed to control the entire supply chain of an industry is known as vertical integration. This type of integration allows a company to handle all aspects of a product's lifecycle, from the creation of raw materials through the production process to the delivery of the final product.
An example of vertical integration in practice was demonstrated by John D. Rockefeller, who, in building his oil empire, invested in and acquired companies involved in every step of the oil refining process, from barrel-making to transportation. This differs from other strategies such as a merger, where two companies combine to form one; horizontal integration, where a company buys out its competitors in the same industry at the same level of production; and forming a cartel, where firms in an oligopoly work together to control the market like a monopoly.
Therefore, the correct option in the final answer for businesses that sought to control the entire supply chain of an industry is B) vertical integration.