B. Most nations had one primary religion.
The Reformation had occurred in the 16th century (the 1500s). By 1600, the positions had solidified, and nations typically were of one religious position or another. Italy, France and Spain and certain other states remained staunchly Roman Catholic. Most of the German states had become Lutheran, as had Scandinavian countries. England had established the Church of England, its own brand of Protestantism. Many cantons in Switzerland had become enclaves of Calvinism. There wasn't much of a notion yet of religious diversity within the same community or society. Each principality or territory tended to have one official religion operating in it.