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: As the terrain is generally arid, the hills have mostly poor soil and support only cacti and succulent plants. During the rainy season the area turns green with vegetation and grass. The eastern part of the island is greener as it receives more rainfall. A 1994 survey has revealed several hundred indigenous species of plants including the naturalized varieties of flora; some growing in irrigated areas while the dry areas are dominated by the cacti variety. Sea grapes and palm trees are a common sight with mangroves and shrubs surviving in the saline coastal swamps. Coconut palm was brought to the island from the Pacific islands. Important plants noted on the island are:

Answer: In what year was Coconut palm brought to the island?


Question: Passage: Sichuan consists of two geographically very distinct parts. The eastern part of the province is mostly within the fertile Sichuan basin (which is shared by Sichuan with Chongqing Municipality). The western Sichuan consists of the numerous mountain ranges forming the easternmost part of the Qinghai-Tibet Plateau, which are known generically as Hengduan Mountains. One of these ranges, Daxue Mountains, contains the highest point of the province Gongga Shan, at 7,556 metres (24,790 ft) above sea level.

Answer: What province has similar eastern and western parts?


Question: Passage: The Houston area has over 150 active faults (estimated to be 300 active faults) with an aggregate length of up to 310 miles (500 km), including the Long Point–Eureka Heights fault system which runs through the center of the city. There have been no significant historically recorded earthquakes in Houston, but researchers do not discount the possibility of such quakes having occurred in the deeper past, nor occurring in the future. Land in some areas southeast of Houston is sinking because water has been pumped out of the ground for many years. It may be associated with slip along the faults; however, the slippage is slow and not considered an earthquake, where stationary faults must slip suddenly enough to create seismic waves. These faults also tend to move at a smooth rate in what is termed "fault creep", which further reduces the risk of an earthquake.

Answer:
 How many estimated unactive faults does Houston have?