Answer:
John D. Rockefeller.
Explanation:
The other options were also among the richest men in the United States but, in the case of Andrew Carnegie, he made his fortune with the Steel industry. While J. P. Morgan was a financier.
John D. Rockefeller started the Standard Oil company in 1870 on Ohio and the corporation grew to be one of the most important monopolies of the entire history until the United States Supreme Court regulated the monopolies on a case against Standard Oil in 1911.
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