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: The so-called "Sack of Palermo" is one of the major visible faces of the problem. The term is used to indicate the speculative building practices that have filled the city with poor buildings. The reduced importance of agriculture in the Sicilian economy has led to a massive migration to the cities, especially Palermo, which swelled in size, leading to rapid expansion towards the north. The regulatory plans for expansion was largely ignored in the boom. New parts of town appeared almost out of nowhere, but without parks, schools, public buildings, proper roads and the other amenities that characterise a modern city.
[A]: What is the term for the building boom erected many fine buildings?


[Q]: Passage: The capital city of Windhoek plays a very important role in Namibia's tourism due to its central location and close proximity to Hosea Kutako International Airport. According to The Namibia Tourism Exit Survey, which was produced by the Millennium Challenge Corporation for the Namibian Directorate of Tourism, 56% of all tourists visiting Namibia during the time period, 2012 - 2013, visited Windhoek. Many of Namibia's tourism related parastatals and governing bodies such as Namibia Wildlife Resorts, Air Namibia and the Namibia Tourism Board as well as Namibia's tourism related trade associations such as the Hospitality Association of Namibia are also all headquartered in Windhoek. There are also a number of notable hotels in Windhoek such as Windhoek Country Club Resort and some international hotel chains also operate in Windhoek, such as Avani Hotels and Resorts and Hilton Hotels and Resorts.
[A]: What percentage of tourists arrive in Namibia at Hosea Kutako International Airport?


[Q]: Passage: Annelids with blood vessels use metanephridia to remove soluble waste products, while those without use protonephridia. Both of these systems use a two-stage filtration process, in which fluid and waste products are first extracted and these are filtered again to re-absorb any re-usable materials while dumping toxic and spent materials as urine. The difference is that protonephridia combine both filtration stages in the same organ, while metanephridia perform only the second filtration and rely on other mechanisms for the first – in annelids special filter cells in the walls of the blood vessels let fluids and other small molecules pass into the coelomic fluid, where it circulates to the metanephridia. In annelids the points at which fluid enters the protonephridia or metanephridia are on the forward side of a septum while the second-stage filter and the nephridiopore (exit opening in the body wall) are in the following segment. As a result, the hindmost segment (before the growth zone and pygidium) has no structure that extracts its wastes, as there is no following segment to filter and discharge them, while the first segment contains an extraction structure that passes wastes to the second, but does not contain the structures that re-filter and discharge urine.
[A]:
What do metanephridia produce?