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: The war had removed Bermuda's primary trading partners, the American colonies, from the empire, and dealt a harsh blow to Bermuda's merchant shipping trade. This also suffered due to the deforestation of Bermuda, as well as the advent of metal ships and steam propulsion, for which it did not have raw materials. During the course of the following War of 1812, the primary market for Bermuda's salt disappeared as the Americans developed their own sources. Control of the Turks had passed to the Bahamas in 1819.
What was the primary market for Bermuda following the War of 1812?

Passage: In Ancient Greece, green and blue were sometimes considered the same color, and the same word sometimes described the color of the sea and the color of trees. The philosopher Democritus described two different greens; cloron, or pale green, and prasinon, or leek green. Aristotle considered that green was located midway between black, symbolizing the earth, and white, symbolizing water. However, green was not counted among of the four classic colors of Greek painting; red, yellow, black and white, and is rarely found in Greek art.
How many blues did Democritus describe?

Passage: It is not clearly documented when the title of the Grand Duke was first introduced, but the importance of the Kiev principality was recognized after the death of Sviatoslav I in 972 and the ensuing struggle between Vladimir the Great and Yaropolk I. The region of Kiev dominated the state of Kievan Rus' for the next two centuries. The Grand Prince ("velikiy kniaz'") of Kiev controlled the lands around the city, and his formally subordinate relatives ruled the other cities and paid him tribute. The zenith of the state's power came during the reigns of Vladimir the Great (980–1015) and Prince Yaroslav I the Wise (1019–1054). Both rulers continued the steady expansion of Kievan Rus' that had begun under Oleg.

When was the title of Grand Duke introduced?