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: The three brothersRurik, Sineus, and Truvorestablished themselves in Novgorod, Beloozero, and Izborsk, respectively. Two of the brothers died, and Rurik became the sole ruler of the territory and progenitor of the Rurik Dynasty. A short time later, two of Rurik's men, Askold and Dir, asked him for permission to go to Tsargrad (Constantinople). On their way south, they discovered "a small city on a hill," Kiev, captured it and the surrounding country from the Khazars, populated the region with more Varangians, and "established their dominion over the country of the Polyanians."

Answer: What were the names of the three sisters that ruled Novgorod, Beloozero, and Izborsk?

Question: Passage: This was also a period of alternatives to nightclubs, the warehouse party, acid house, rave and outdoor festival scenes of the late 1980s and early 1990s were havens for the latest trends in electronic dance music, especially house and its ever-more hypnotic, synthetic offspring techno and trance, in clubs like the infamous Warsaw Ballroom better known as Warsaw and The Mix where DJs like david padilla (who was the resident DJ for both) and radio. The new sound fed back into mainstream clubs across the country. The scene in SoBe, along with a bustling secondhand market for electronic instruments and turntables, had a strong democratizing effect, offering amateur, "bedroom" DJs the opportunity to become proficient and popular as both music players and producers, regardless of the whims of the professional music and club industries. Some of these notable DJs are John Benetiz (better known as JellyBean Benetiz), Danny Tenaglia, and David Padilla.

Answer: Who was the Warsaw Ballroom's house JD?

Question: Passage: Environmental sustainability has become a mainstream issue, with profound effect on the architectural profession. Many developers, those who support the financing of buildings, have become educated to encourage the facilitation of environmentally sustainable design, rather than solutions based primarily on immediate cost. Major examples of this can be found in Passive solar building design, greener roof designs, biodegradable materials, and more attention to a structure's energy usage. This major shift in architecture has also changed architecture schools to focus more on the environment. Sustainability in architecture was pioneered by Frank Lloyd Wright, in the 1960s by Buckminster Fuller and in the 1970s by architects such as Ian McHarg and Sim Van der Ryn in the US and Brenda and Robert Vale in the UK and New Zealand. There has been an acceleration in the number of buildings which seek to meet green building sustainable design principles. Sustainable practices that were at the core of vernacular architecture increasingly provide inspiration for environmentally and socially sustainable contemporary techniques. The U.S. Green Building Council's LEED (Leadership in Energy and Environmental Design) rating system has been instrumental in this.

Answer:
What issue has moved to the forefront in past years?