What is meant by the term "Counter-Reformation"?

The term "Counter-Reformation" specifically refers to the Catholic Church's response to the rise of Protestantism during the 16th century. This movement aimed to address the criticisms of the Church raised by Protestant reformers such as Martin Luther and John Calvin. It included various measures intended to reform the Church from within, reaffirming key doctrines, improving clerical education, and combating corruption. The Council of Trent (1545-1563) played a crucial role in defining Catholic doctrine and addressing issues of discipline and reform.

While other options pertain to historical movements or events, they do not directly relate to the specific challenge posed by Protestantism and the consequent actions taken by the Catholic Church. Hence, the focus and significance of the Counter-Reformation lie distinctly in its effort to maintain Catholic doctrine and practices in the face of evolving religious perspectives stemming from the Reformation.