Western Historians Have Customarily Regarded This as the Crucial Point

Western historians have customarily regarded this as the crucial point in opening the trade routes to the East.

A) the travels of Marco Polo
B) the voyages of Vasco de Gama
C) the discovery of the New World by Columbus
D) Magellan's circumnavigation of the globe
E) Prince Henry, the Navigator's establishment of a school for navigators