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.

Passage: Conventional bleaching of wood pulp using elemental chlorine produces and releases into the environment large amounts of chlorinated organic compounds, including chlorinated dioxins. Dioxins are recognized as a persistent environmental pollutant, regulated internationally by the Stockholm Convention on Persistent Organic Pollutants. Dioxins are highly toxic, and health effects on humans include reproductive, developmental, immune and hormonal problems. They are known to be carcinogenic. Over 90% of human exposure is through food, primarily meat, dairy, fish and shellfish, as dioxins accumulate in the food chain in the fatty tissue of animals.
What does bleaching of meat release into the environment?

Passage: Wildfires plague the forested areas of Guam every dry season despite the island's humid climate. Most fires are man-caused with 80% resulting from arson. Poachers often start fires to attract deer to the new growth. Invasive grass species that rely on fire as part of their natural life cycle grow in many regularly burned areas. Grasslands and "barrens" have replaced previously forested areas leading to greater soil erosion. During the rainy season sediment is carried by the heavy rains into the Fena Lake Reservoir and Ugum River, leading to water quality problems for southern Guam. Eroded silt also destroys the marine life in reefs around the island. Soil stabilization efforts by volunteers and forestry workers (planting trees) have had little success in preserving natural habitats.
What are 20% of fires resulting from?

Passage: In these schools children could be selected on the basis of curriculum aptitude related to the school's specialism even though the schools do take quotas from each quartile of the attainment range to ensure they were not selective by attainment. A problem with this is whether the quotas should be taken from a normal distribution or from the specific distribution of attainment in the immediate catchment area. In the selective school system, which survives in several parts of the United Kingdom, admission is dependent on selection criteria, most commonly a cognitive test or tests. Although comprehensive schools were introduced to England and Wales in 1965, there are 164 selective grammar schools that are still in operation.[citation needed] (though this is a small number compared to approximately 3500 state secondary schools in England). Most comprehensives are secondary schools for children between the ages of 11 to 16, but in a few areas there are comprehensive middle schools, and in some places the secondary level is divided into two, for students aged 11 to 14 and those aged 14 to 18, roughly corresponding to the US middle school (or junior high school) and high school, respectively. With the advent of key stages in the National Curriculum some local authorities reverted from the Middle School system to 1116 and 1118 schools so that the transition between schools corresponds to the end of one key stage and the start of another.
How many selective high schools are still currently functioning in England and Wales?