Final answer:
The correct answer is option a) Rockefeller's personal wealth increased significantly after the breakup.
Step-by-step explanation:
The breakup of the Standard Oil Company had an unexpected positive impact on John D. Rockefeller's personal finances. Instead of losing money, Rockefeller's wealth actually increased as he received proportional shares in each of the smaller companies that Standard Oil was broken into.
These companies, which included the precursors to modern-day giants like Exxon and Chevron, proved to be highly successful on their own. Consequently, as these companies' values grew, so too did Rockefeller's wealth in the form of his holdings in these entities, making him even richer than he was before the breakup.