a) The Muslim empire was in decline for a long time now. Internal problems were causing political turmoil. The main cause however of the Abbasids' fall was outside invasions by the nomadic war machine known as the Mongols. In 1258 the Mongols finally captured the capital of Baghdad. The last of the Abbasid caliphs were killed by them and slaughtered many. The Muslim's culture suffered, and they viewed their new rulers as barbarians.
b) Europe faced many problems coming into the 1400s but still remained strong surprisingly. Although the Black Plague was spreading and the standard of living for commoners was dwindling, the institutions of Europe kept it strong and enduring. Europe went through a long period of feudalism, from which regional monarchies emerged. These kept areas partly unified and organized. Also, the Hundred Years War brought new military innovations to Europe. In addition, there was the growth of cities too, brought on by the increase in commerce caused by the formation of towns after the decline of manorialism. The church also supported capitalism. Moreover, there were improvements in the technology of the west, especially in metallurgy.
c) Beginning in the 1400s, the Renaissance was important in benefiting European society. One big advancement was the large increase in banking and trading. This led to the development of more and more cities and significant economic growth. Also, Europe began to flourish culturally. Works became more secular with a strong focus on humanism and portrait paintings. Artists and writers pushed for their own reputation making themselves well known. The wealthy became patrons of the arts, usually to have works of art to impress others. In addition, there was a changing mindset, as people began to look outward. They began to build better ships, pushed commerce, and put their interest in exploring and possibly colonizing new lands beyond their own.