Answer:
John D. Rockefeller and Andrew Carnegie increased the size of their business by creating monopolies that concentrated all the market of their respective interests (oil in the case of Rockefeller, and steel in the case of Carnegie) by buying all the competence.
Step-by-step explanation:
-John Davison Rockefeller was an American entrepreneur and investor who worked in the world of the oil industry, reaching the point of monopolizing it. He was the founder and president of Standard Oil, a giant company that came to control the extraction, refining, transportation and distribution of more than 90% of US oil and held entire monopolies (in the form of investments) in multiple foreign countries. Over a period of more than forty years, Rockefeller consolidated Standard Oil as the world's largest oil company, revolutionizing the industry at all levels and demonstrating an extraordinary and relentless competitive ability. On the other hand, Rockefeller devoted much of his fortune and resources to numerous donations, foundations and programs, being the founder of the University of Chicago, one of the most prestigious universities in the world, the birthplace of 87 Nobel Laureates, as well as the Rockefeller University in New York, besides boosting numerous areas of education, science and medicine.
-Andrew Carnegie was an American industrialist, businessman and philanthropist from Scotland. As a child, he emigrated from Scotland with his parents. He worked from a very young age on the Pennsylvania Railroad Company. At age 20 he became manager of the same railroad company and the apprentice of Thomas A. Scott, owner of the company.
He created the Carnegie Steel Company in Pittsburgh, which later merged with the Federal Steel Company of Elbert H. Gary and with several smaller companies to create U.S. Steel. The fortune he earned from his businesses was spent on philanthropy and education, founding the Carnegie Corporation of New York, the Carnegie Endowment for International Peace, and Carnegie Mellon University in Pittsburgh.