The correct answer is option 3, "The revolt against authority of the pope." The Reformation was a religious and political movement that emerged in the 16th century in Europe. It was characterized by a rebellion against the authority of the Roman Catholic Church and its pope. This revolt was led by figures such as Martin Luther and John Calvin who challenged the practices and doctrines of the Church, advocating for reform and a return to a more biblical understanding of Christianity. The Reformation had significant political and social impacts, leading to the establishment of Protestant churches, the decline of the power of the Catholic Church, and the emergence of new religious and intellectual currents. It is important to note that while the other options may have been relevant in the context of the broader historical developments of the time, they do not accurately describe the essence of the Reformation.