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.

[Q]: Passage: Subsequently, in October 2001, U.S. forces (with UK and coalition allies) invaded Afghanistan to oust the Taliban regime. On 7 October 2001, the official invasion began with British and U.S. forces conducting airstrike campaigns over enemy targets. Kabul, the capital city of Afghanistan, fell by mid-November. The remaining al-Qaeda and Taliban remnants fell back to the rugged mountains of eastern Afghanistan, mainly Tora Bora. In December, Coalition forces (the U.S. and its allies) fought within that region. It is believed that Osama bin Laden escaped into Pakistan during the battle.
[A]: What city fell by mid-October in the invasion of Afghanistan?

[Q]: Passage: Approximately 10,000 years ago, desertification forced hunter-gatherer societies south into the Sahel regions of northern Central Africa, where some groups settled and began farming as part of the Neolithic Revolution. Initial farming of white yam progressed into millet and sorghum, and before 3000 BC the domestication of African oil palm improved the groups' nutrition and allowed for expansion of the local populations. Bananas arrived in the region and added an important source of carbohydrates to the diet; they were also used in the production of alcoholic beverages.[when?] This Agricultural Revolution, combined with a "Fish-stew Revolution", in which fishing began to take place, and the use of boats, allowed for the transportation of goods. Products were often moved in ceramic pots, which are the first known examples of artistic expression from the region's inhabitants.
[A]: How long ago did farming force hunter-gatherer societies south?

[Q]: Passage: A railway electrification system supplies electric power to railway trains and trams without an on-board prime mover or local fuel supply. Electrification has many advantages but requires significant capital expenditure. Selection of an electrification system is based on economics of energy supply, maintenance, and capital cost compared to the revenue obtained for freight and passenger traffic. Different systems are used for urban and intercity areas; some electric locomotives can switch to different supply voltages to allow flexibility in operation.
[A]:
What system supplies nuclear power to railway trains?