Which Statement Most Accurately Captures the Significance of Columbus's Voyages

Which statement most accurately captures the significance of Columbus's voyages to the Americas?

A) His expeditions initiated extensive contact between the continents of the Old and New Worlds, resulting in the radical biological transformations of both regions.
B) By claiming the Americas for Spain, he ensured that the New World enjoyed the dominance of tolerant and enlightened European peoples.
C) His journey disproved the widely held belief that the earth was flat and almost single-handedly inspired a more rational and empirical approach to understanding the natural world.
D) Without Columbus's unique bravery and geographical insight, contact between the Americas and Europe might never have occurred.