The correct answer is Christopher Columbus. Christopher Columbus is historically credited with the "discovery" of the Americas (the "New World") when he arrived in the Caribbean in 1492. While it is important to note that indigenous peoples had inhabited the continents for thousands of years prior, and Viking explorer Leif Erikson had made earlier voyages to North America, Columbus's expeditions marked the beginning of sustained European exploration, colonization, and interaction with the Americas. His voyages were pivotal in shaping the course of history for the continents that would eventually include the United States of America, from a Eurocentric historical perspective.
Option A, Marco Polo, is incorrect. Marco Polo was a Venetian merchant and explorer renowned for his extensive travels through Asia, particularly to China, in the 13th century. He never ventured to the Americas.
Option C, Magellan, is incorrect. Ferdinand Magellan was a Portuguese explorer who organized the Spanish expedition of 1519-1522, which resulted in the first circumnavigation of the Earth. While his voyage was monumental, it did not involve the discovery of the landmass that would become the USA.
Option D, Ibn-e-Battuta, is incorrect. Ibn Battuta was a famous Moroccan explorer who traveled extensively across Africa, the Middle East, Asia, and parts of Europe in the 14th century. His travels did not include the Americas.