The correct answer is A. Christopher Columbus.
Christopher Columbus was an Italian explorer and navigator who completed four voyages across the Atlantic Ocean, opening the way for the widespread European exploration and colonization of the Americas. He has been credited for discovering the New World.
Vasco da Gama was a Portuguese explorer who was the first European to sail directly from Europe to India. He is considered to be one of the most important figures in the Age of Discovery.
James Cook was a British explorer and navigator who is best known for his three voyages to the Pacific Ocean. He is considered to be one of the greatest explorers of all time.
None of the other options are correct.