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.
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Question: Passage: From the 19th century, there was a revival in many ancient glass-making techniques including cameo glass, achieved for the first time since the Roman Empire and initially mostly used for pieces in a neo-classical style. The Art Nouveau movement made great use of glass, with René Lalique, Émile Gallé, and Daum of Nancy producing colored vases and similar pieces, often in cameo glass, and also using luster techniques. Louis Comfort Tiffany in America specialized in stained glass, both secular and religious, and his famous lamps. The early 20th-century saw the large-scale factory production of glass art by firms such as Waterford and Lalique. From about 1960 onwards there have been an increasing number of small studios hand-producing glass artworks, and glass artists began to class themselves as in effect sculptors working in glass, and their works as part fine arts.

Answer: What famous lampmaker used factory production?


Question: Passage: The Quran describes itself as "the discernment" (al-furqān), "the mother book" (umm al-kitāb), "the guide" (huda), "the wisdom" (hikmah), "the remembrance" (dhikr) and "the revelation" (tanzīl; something sent down, signifying the descent of an object from a higher place to lower place). Another term is al-kitāb (The Book), though it is also used in the Arabic language for other scriptures, such as the Torah and the Gospels. The adjective of "Quran" has multiple transliterations including "quranic", "koranic", and "qur'anic", or capitalised as "Qur'anic", "Koranic", and "Quranic". The term mus'haf ('written work') is often used to refer to particular Quranic manuscripts but is also used in the Quran to identify earlier revealed books. Other transliterations of "Quran" include "al-Coran", "Coran", "Kuran", and "al-Qurʼan".

Answer: Which term meaning "the mother book" doesn't the Quran apply to itself?


Question: Passage: Older operating systems such as TOPS-10, along with CP/M, tracked file length only in units of disk blocks and used Control-Z (SUB) to mark the end of the actual text in the file. For this reason, EOF, or end-of-file, was used colloquially and conventionally as a three-letter acronym for Control-Z instead of SUBstitute. The end-of-text code (ETX), also known as Control-C, was inappropriate for a variety of reasons, while using Z as the control code to end a file is analogous to it ending the alphabet and serves as a very convenient mnemonic aid. A historically common and still prevalent convention uses the ETX code convention to interrupt and halt a program via an input data stream, usually from a keyboard.

Answer:
What did older operating systems use to mark control code?