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.

Ex Input:
Passage: Since World War II, aircraft carrier designs have increased in size to accommodate a steady increase in aircraft size. The large, modern Nimitz class of US carriers has a displacement nearly four times that of the World War IIera USS Enterprise, yet its complement of aircraft is roughly the samea consequence of the steadily increasing size and weight of military aircraft over the years. Today's aircraft carriers are so expensive that nations which operate them risk significant political, economic, and military impact if a carrier is lost, or even used in conflict.

Ex Output:
Why have aircraft carriers increased in size since World War I?

Ex Input:
Passage: The climate of Antarctica does not allow extensive vegetation to form. A combination of freezing temperatures, poor soil quality, lack of moisture, and lack of sunlight inhibit plant growth. As a result, the diversity of plant life is very low and limited in distribution. The flora of the continent largely consists of bryophytes. There are about 100 species of mosses and 25 species of liverworts, but only three species of flowering plants, all of which are found in the Antarctic Peninsula: Deschampsia antarctica (Antarctic hair grass), Colobanthus quitensis (Antarctic pearlwort) and the non-native Poa annua (annual bluegrass). Growth is restricted to a few weeks in the summer.

Ex Output:
What allows extensive vegitation to occur?

Ex Input:
Passage: Stepper motors were and still are often used in computer printers, optical scanners, and digital photocopiers to move the optical scanning element, the print head carriage (of dot matrix and inkjet printers), and the platen or feed rollers. Likewise, many computer plotters (which since the early 1990s have been replaced with large-format inkjet and laser printers) used rotary stepper motors for pen and platen movement; the typical alternatives here were either linear stepper motors or servomotors with closed-loop analog control systems.

Ex Output:
List two alternatives to rotary stepper motors in non-printer applications.