Final answer:
The major effect of the Crusades on western Europeans was the introduction of advances developed in Muslim countries. This exposure led to an increased interest in trade and exploration.
Step-by-step explanation:
The major effect of the Crusades on western Europeans was that they were introduced to advances developed in Muslim countries. When Catholic Crusaders returned from the Middle East, they brought back tales of new lands, new peoples, and new goods that they had never experienced before. This exposure led to an increased interest in trade and exploration, which eventually contributed to the Age of Exploration.