Given the following 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.",  answer the following question. Note that the answer is present within the text.  Question: What led to the discovery of the Americas?
A:
the expedition of Christopher Columbus