How did the Crusades bring about the end of the Dark Ages in Europe? What was the "spark in the dark" that ended the "darkness" of the Middle Ages

AScience-Europeans were able to study the stars (astronomy) the way that the Muslims had already been studying astronomy

BEngineering-Europeans were able to study new designs of building that had already been introduced in the Muslim "world"

CEducation-Europeans were able to study new forms of mathematics that were already being studied in the Muslim "world"

DWealth of Knowledge-so much information was brought back from the Muslim "world"; information pertaining to medical knowledge, new forms of mathematics and education, "Aristotle was brought back," and "everything was brought back"; so many new ideas were brought back to Europe from the Muslim "world"