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: In the floor, just inside the great west door, in the centre of the nave, is the tomb of The Unknown Warrior, an unidentified British soldier killed on a European battlefield during the First World War. He was buried in the abbey on 11 November 1920. This grave is the only one in the abbey on which it is forbidden to walk.[citation needed]
When was The Known Warrior buried?

Passage: The revisionist paleontologist Robert T. Bakker, who published his findings as The Dinosaur Heresies, treated the mainstream view of dinosaurs as dogma. "I have enormous respect for dinosaur paleontologists past and present. But on average, for the last fifty years, the field hasn't tested dinosaur orthodoxy severely enough." page 27 "Most taxonomists, however, have viewed such new terminology as dangerously destabilizing to the traditional and well-known scheme..." page 462. This book apparently influenced Jurassic Park. The illustrations by the author show dinosaurs in very active poses, in contrast to the traditional perception of lethargy. He is an example of a recent scientific endoheretic.
Who is a modern example of an exoheretic?

Passage: Yazid died while the siege was still in progress, and the Umayyad army returned to Damascus, leaving Ibn al-Zubayr in control of Mecca. Yazid's son Muawiya II (683–84) initially succeeded him but seems to have never been recognized as caliph outside of Syria. Two factions developed within Syria: the Confederation of Qays, who supported Ibn al-Zubayr, and the Quda'a, who supported Marwan, a descendant of Umayya via Wa'il ibn Umayyah. The partisans of Marwan triumphed at a battle at Marj Rahit, near Damascus, in 684, and Marwan became caliph shortly thereafter.

What army left Damascus?