The best option that illustrates the reasons for major shifts in religious beliefs during the Protestant Reformation is:
C. Religious institutions’ failures to respond to ideas for change cause people to seek or create new institutions.
The Protestant Reformation was driven by widespread dissatisfaction with the Catholic Church, particularly regarding its practices and doctrines. As reformers like Martin Luther criticized the church's failures to address these issues, many followers sought alternatives, ultimately leading to the establishment of new Protestant denominations.