Detailed Instructions: 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.
Problem:Passage: In 1469, following the Treaty of St. Omer, Upper Alsace was sold by Archduke Sigismund of Austria to Charles the Bold, Duke of Burgundy. Although Charles was the nominal landlord, taxes were paid to Frederick III, Holy Roman Emperor. The latter was able to use this tax and a dynastic marriage to his advantage to gain back full control of Upper Alsace (apart from the free towns, but including Belfort) in 1477 when it became part of the demesne of the Habsburg family, who were also rulers of the empire. The town of Mulhouse joined the Swiss Confederation in 1515, where it was to remain until 1798.
Solution:
What did Charles the Bold sell to Archduke Sigismund?