The correct answer is B: they opened sea routes that allowed Europeans to trade directly with Asia.
On the one hand, Bartolomeu Dias sailed around the Cape of Good Hope, the southern tip of Africa and as a consequence he discovered that the Indian and the Atlantic Oceans flowed into each other proving that the Indian Ocean was not land-Locked. Later on, Vasco da Gama sailed around the Cape of Good Hope as well discovering a sea route that would give way to a future successful trade by sea, especially for Portuguese people.
