Final answer:
John D. Rockefeller did not engage in unionization as he built his oil empire; instead, he focused on practices such as horizontal integration, vertical integration, and philanthropy.
Step-by-step explanation:
As John D. Rockefeller built his company into a vast success, he adopted several management strategies. However, one approach he did not undertake as part of his business practices was unionization. Rockefeller was known for his use of horizontal integration, which involved merging with other companies or driving competition out of the market. He also famously utilized vertical integration, controlling all aspects of a product's lifecycle, and engaged in significant philanthropy. Nonetheless, unionization was a key goal for striking workers during the time and would not have aligned with Rockefeller's business model focused on minimizing costs and maintaining strict control over his workforce.