The voyages of Christopher Columbus led to the first lasting European contact with the Americas, inaugurating a period of European exploration, conquest, and colonization that lasted for several centuries. Columbus was not the first European explorer to reach the Americas having been preceded by the Norse expedition led by Leif Erikson in the 11th century. Leif Erikson was an Icelandic explorer considered by some as the first European to land in North America (excluding Greenland), before Columbus. There is much debate as some say that many different people, spanning centuries, set foot on the New World (as the Americas were called) before Columbus, and, of course, the ancestors of the Native Americans had already discovered it many years before.
One of the main reasons why a historian would use a primary source when studying a historical event is because "<span>C. Primary sources are created by people who actually experienced the event", and they can also be things that happened to be "around" at a certain time. </span>
He took control of Eastern Europe. hop this helps! ;)
Pretty sure it's B
Hope it helps