The key factor which fueled competition between European countries for colonies in the Americas was C) the desire to control sources of gold and silver. Although Europe did have certain resources, it had definitely depleted itself in gold and silver and there was a sort of race between the big European super powers to enrich themselves as much as they could. This can be especially seen with the silver mines in Mexico which both the Spanish and the French wanted to acquire.
That would be Urbanization, the process of making a place in nature into a habitat for humans.
The imrpoved agricultural techniques, such as the three field system, the climate change, and the horse plows. These effected Western Europe during the middle ages because the three field system produced better crops, the climate opened more land to farming, and the horse plows allowed faster harvesting. This made life a lot easier for farmers.
