c) James K. Polk

James K. Polk, the 11th President of the United States, is known for overseeing a significant expansion of U.S. territory. His presidency, from 1845 to 1849, was marked by the annexation of Texas and the acquisition of the Oregon Territory. Polk’s expansionist agenda, often termed “Manifest Destiny,” reflected the widespread belief in the United States’ right and destiny to expand across the North American continent. The annexation of Texas, which led to the Mexican-American War, and the negotiation of the Oregon Territory’s northern boundary with Great Britain were key achievements of his administration. These actions significantly enlarged the nation’s territory and shaped its future growth and development.