<span>B. valve cover. is the answer</span>
The main way in which artisan guilds changed labor and social class in medieval Europe is that it gave the artisans, who were mostly members of the lower class, more power--since these guilds acted somewhat like a modern "union" and helped them negotiate better pay.
C, Yorktown because the French went to Yorktown to join the colonists and fight with them
The mountain men era ended because the beaver was almost drove to extinction in that area and because of fashion. Yes, the change of fashion caused the mountain men era to end. Afterward though many of them became a guide for that area since they had lived there for while.
