Teacher: 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.
Teacher: Now, understand the problem? If you are still confused, see the following example:
Passage: In 1763, Spain traded Florida to the Kingdom of Great Britain for control of Havana, Cuba, which had been captured by the British during the Seven Years' War. It was part of a large expansion of British territory following the country's victory in the Seven Years' War. Almost the entire Spanish population left, taking along most of the remaining indigenous population to Cuba. The British soon constructed the King's Road connecting St. Augustine to Georgia. The road crossed the St. Johns River at a narrow point, which the Seminole called Wacca Pilatka and the British named "Cow Ford", both names ostensibly reflecting the fact that cattle were brought across the river there.
Solution: Who owned Cuba after the Eight Years War?
Reason: This question appears to be relevant to the passage as both involves words such as 'Cuba' and 'War' which also exist in the passage. The passage mentions that "after the war, almost the entire Spanish population left, taking along most of the remaining indigenous population to Cuba". This information is not sufficient to conclude that which country owned cuba.

Now, solve this instance: Passage: Selfridges was established in 1909 by American-born Harry Gordon Selfridge on Oxford Street. The company's innovative marketing promoted the radical notion of shopping for pleasure rather than necessity and its techniques were adopted by modern department stores the world over. The store was extensively promoted through paid advertising. The shop floors were structured so that goods could be made more accessible to customers. There were elegant restaurants with modest prices, a library, reading and writing rooms, special reception rooms for French, German, American and "Colonial" customers, a First Aid Room, and a Silence Room, with soft lights, deep chairs, and double-glazing, all intended to keep customers in the store as long as possible. Staff members were taught to be on hand to assist customers, but not too aggressively, and to sell the merchandise. Selfridge attracted shoppers with educational and scientific exhibits; in 1909, Louis Bleriot's monoplane was exhibited at Selfridges (Bleriot was the first to fly over the English Channel), and the first public demonstration of television by John Logie Baird took place in the department store in 1925.
Student:
Who founded Selfridges in 1990?