Final answer:
Portugal became the leader in trade and empire-building during the Age of Exploration.
Step-by-step explanation:
The European country that became a leader in trade and empire-building during the Age of Exploration was Portugal. Portugal established a vast trading network and was the first European power to sail around Africa to India, establishing several trading ports along the way. Their explorations were led by famous navigators like Vasco da Gama and Ferdinand Magellan, who helped expand Portugal's empire and dominance in trade.
Learn more about Europe's leadership in trade and empire-building during the Age of Exploration