Final answer:
John D. Rockefeller did not use cooperative agreements to grow his empire; his strategies included horizontal integration, vertical integration, and predatory pricing.
Step-by-step explanation:
Rockefeller was notorious for his aggressive business strategies to ensure he controlled the oil industry; however, cooperative agreements were not one of his tactics. Instead, his pursuit of power included techniques such as horizontal integration, where he expanded by buying out competitors or merging with them, vertical integration, taking over all aspects of the production and distribution process, and predatory pricing, lowering prices to a point where his competitors couldn't compete and were forced to exit the market.
Rockefeller's use of horizontal integration was notably effective, resulting in his Standard Oil Company controlling an overwhelming majority of the oil refineries by the 1870s, but cooperative agreements between rival firms to set market conditions or prices were not a part of his playbook. His strategies are often associated with practices that eventually led to the implementation of antitrust laws, like the Sherman Antitrust Act, to prevent such monopolistic dominance in the future.