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: Downtown San Diego is the central business district of San Diego, though the city is filled with business districts. These include Carmel Valley, Del Mar Heights, Mission Valley, Rancho Bernardo, Sorrento Mesa, and University City. Most of these districts are located in Northern San Diego and some within North County regions.
What is the central business district of downtown San Diego?

Passage: The French population numbered about 75,000 and was heavily concentrated along the St. Lawrence River valley, with some also in Acadia (present-day New Brunswick and parts of Nova Scotia, including Île Royale (present-day Cape Breton Island)). Fewer lived in New Orleans, Biloxi, Mississippi, Mobile, Alabama and small settlements in the Illinois Country, hugging the east side of the Mississippi River and its tributaries. French fur traders and trappers traveled throughout the St. Lawrence and Mississippi watersheds, did business with local tribes, and often married Indian women. Traders married daughters of chiefs, creating high-ranking unions.
What wasn't the French population in North America?

Passage: During the late medieval period, cotton became known as an imported fiber in northern Europe, without any knowledge of how it was derived, other than that it was a plant. Because Herodotus had written in his Histories, Book III, 106, that in India trees grew in the wild producing wool, it was assumed that the plant was a tree, rather than a shrub. This aspect is retained in the name for cotton in several Germanic languages, such as German Baumwolle, which translates as "tree wool" (Baum means "tree"; Wolle means "wool"). Noting its similarities to wool, people in the region could only imagine that cotton must be produced by plant-borne sheep. John Mandeville, writing in 1350, stated as fact the now-preposterous belief: "There grew there [India] a wonderful tree which bore tiny lambs on the endes of its branches. These branches were so pliable that they bent down to allow the lambs to feed when they are hungrie  [sic]." (See Vegetable Lamb of Tartary.) By the end of the 16th century, cotton was cultivated throughout the warmer regions in Asia and the Americas.

What was cotton viewed as in the late medieval period in Asia?