Given the task definition, example input & output, solve the new input case.
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.
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.
Output: Who owned Cuba after the Eight Years War?
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.

New input case for you: Passage: During the First World War, to avoid ground fights between brothers, many Alsatians served as sailors in the Kaiserliche Marine and took part in the Naval mutinies that led to the abdication of the Kaiser in November 1918, which left Alsace-Lorraine without a nominal head of state. The sailors returned home and tried to found a republic. While Jacques Peirotes, at this time deputy at the Landrat Elsass-Lothringen and just elected mayor of Strasbourg, proclaimed the forfeiture of the German Empire and the advent of the French Republic, a self-proclaimed government of Alsace-Lorraine declared independence as the "Republic of Alsace-Lorraine". French troops entered Alsace less than two weeks later to quash the worker strikes and remove the newly established Soviets and revolutionaries from power. At the arrival of the French soldiers, many Alsatians and local Prussian/German administrators and bureaucrats cheered the re-establishment of order (which can be seen and is described in detail in the reference video below). Although U.S. President Woodrow Wilson had insisted that the region was self-ruling by legal status, as its constitution had stated it was bound to the sole authority of the Kaiser and not to the German state, France tolerated no plebiscite, as granted by the League of Nations to some eastern German territories at this time, because Alsatians were considered by the French public as fellow Frenchmen liberated from German rule. Germany ceded the region to France under the Treaty of Versailles.
Output:
During what war were Alsatians primarily ground units?