Final answer:
The Peace of Augsburg, signed in 1555, legitimized Protestantism for the first time in Europe, allowing rulers in the Holy Roman Empire to choose the religion of their territories.
Step-by-step explanation:
The correct answer is c) Peace of Augsburg.
The Peace of Augsburg was a peace agreement signed in 1555 that ended the Wars of the Lutheran Reformation and legitimized Protestantism for the first time in Europe. It allowed rulers in the Holy Roman Empire to choose the religion of their territories, either Catholicism or Lutheranism. The treaty granted Lutherans the right to establish Lutheranism as the official religion within their lands if they wished, while subjects were obliged to support the church chosen by their ruler.