The correct answer is - A) Dias reached the tip of Africa, while de Gama sailed around it.
Bartolomeu Dias was a Portuguese explorer that managed to be the first one to reach the southernmost tip of the African continent, as well as go around it and enter the Indian Ocean. He was the one that found out the new route towards Asia so that the trade can continue with the European countries.
Vasco de Gama, on the other hand, was the first one to actually use the set up route by Dias, so he is the one that managed to make the actual connection and trade with Asia.