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: As one of the earliest centers of book-printing in Europe (see above: History), Strasbourg for a long time held a large number of incunabuladocuments printed before 1500in her library as one of her most precious heritages. After the total destruction of this institution in 1870, however, a new collection had to be reassembled from scratch. Today, Strasbourg's different public and institutional libraries again display a sizable total number of incunabula, distributed as follows: Bibliotheque nationale et universitaire, ca. 2 098 Mediatheque de la ville et de la communaute urbaine de Strasbourg, 394 Bibliotheque du Grand Seminaire, 238 Mediatheque protestante, 94 and Bibliotheque alsatique du Credit Mutuel, 5.
A:
In what year did book-printing begin in Strasbourg?