c) J.P. Morgan

J.P. Morgan, an influential banker and financier, played a crucial role in the development of the American economy during the late 19th and early 20th centuries. He reorganized and stabilized several major railroads and was instrumental in financing the creation of U.S. Steel Corporation, the world’s first billion-dollar corporation. Morgan’s ability to mobilize and manage large capital resources helped shape the modern corporate economy. His actions during the Panic of 1907, where he organized a coalition of bankers to bail out struggling financial institutions, underscored his significant influence on American finance and banking.