Final answer:
In the court cases U.S vs. Standard Oil, John D. Rockefeller answered most of the charges by denying any wrongdoing and claiming that his business practices were legal.
Step-by-step explanation:
In the court cases U.S vs. Standard Oil, John D. Rockefeller answered most of the charges by denying any wrongdoing and claiming that his business practices were legal (option a). He utilized the trust, a form of corporate management/ownership, to control various oil companies and their decisions without directly owning them. Rockefeller's Standard Oil Trust allowed him to maintain control and reap the majority of profits, all within the bounds of the law.