Which was an important cause of the protestant reformation?

a) a revolt by peasants in germany against the catholic church

b) the catholic clergy refused to perform their duties

c) rulers in northern europe resented the power of the catholic church

d) the muslim religion became more popular in northern europe

The correct answer should be A) a revolt by peasants in Germany against the Catholic Church

That is because the commoners were highly dissatisfied with the fact that the church was selling indulgences which many believed was fraudulent. God can forgive sinners even without indulgences as it is up to the sinner to repent, not just buy his way into heaven.