Why is vasco da gama's voyage in 1499 significant in a global context?
a. it supported columbus' claim that the world was round
b. it demonstrated that there was a faster passage to asia than the traditional overland routes
c. it showed the south and east asian empires that europe was a mighty trading power and foreshadowed europe's coming dominance
d. it opened the doors to direct maritime trading and to establish permanent links between europe and asia