Final answer:
The Catholic Church's response to the spread of Protestantism included the Council of Trent in 1545, which reinforced Catholic doctrines and initiated church reforms to address issues that had fostered the Protestant Reformation.
Step-by-step explanation:
Counter-Reformation Efforts to Contain Protestantism
One method the Catholic Church used to contain the spread of Protestantism was the convening of the Council of Trent in 1545 as part of the Catholic Reformation or Counter-Reformation. This council was pivotal in reforming church practices and reaffirming Catholic doctrines.
The Council of Trent confirmed that both good works and faith were necessary for salvation and maintained that both scripture and tradition were authoritative under the Church's interpretation. Reforms emphasized the education of clergy, prohibition on the sale of indulgences, and regulations against nepotism within the Church hierarchy. As a response to the Protestant challenge, these measures aimed to both clarify Catholic teachings and address the issues that had contributed to the Reformation.