Detailed Instructions: This task is about creating an unanswerable question based on a given passage. Construct a question that looks relevant to the given context but is unanswerable. Following are a few suggestions about how to create unanswerable questions:
(i) create questions which require satisfying a constraint that is not mentioned in the passage
(ii) create questions which require information beyond what is provided in the passage in order to answer
(iii) replace an existing entity, number, date mentioned in the passage with other entity, number, date and use it in the question
(iv) create a question which is answerable from the passage and then replace one or two words by their antonyms or insert/remove negation words to make it unanswerable.
Q: Passage: Roman Catholicism was the sole established religion in the Holy Roman Empire until the Reformation changed this drastically. In 1517, Martin Luther challenged the Catholic Church as he saw it as a corruption of Christian faith. Through this, he altered the course of European and world history and established Protestantism. The Thirty Years' War (16181648) was one of the most destructive conflicts in European history. The war was fought primarily in what is now Germany, and at various points involved most of the countries of Europe. The war was fought largely as a religious conflict between Protestants and Catholics in the Holy Roman Empire.
A:
What was the sole religion in Europe until the reformation?