Q:I want to test the ability of students to read a passage and answer questions about it. Could you please come up with a good question for the passage "The 1469 marriage of Isabella I of Castile and Ferdinand II of Aragon and the 1479 death of John II of Aragon led to the creation of modern-day Spain. In 1492, Granada was captured from the Moors, thereby completing the Reconquista. Portugal had during the 15th century – particularly under Henry the Navigator – gradually explored the coast of Africa, and in 1498, Vasco da Gama found the sea route to India. The Spanish monarchs met the Portuguese challenge by financing the expedition of Christopher Columbus to find a western sea route to India, leading to the discovery of the Americas in 1492."?
A:
Who explored the African coast in the 15th century?