Problem: American Idol:

Season ten of the series premiered on January 19, 2011. Many changes were introduced this season, from the format to the personnel of the show. Jennifer Lopez and Steven Tyler joined Randy Jackson as judges following the departures of Simon Cowell (who left to launch the U.S. version of The X Factor), Kara DioGuardi (whose contract was not renewed) and Ellen DeGeneres, while Nigel Lythgoe returned as executive producer. Jimmy Iovine, chairman of the Interscope Geffen A&M label group, the new partner of American Idol, acted as the in-house mentor in place of weekly guest mentors, although in later episodes special guest mentors such as Beyoncé, will.i.am and Lady Gaga were brought in.

What year did season ten of American Idol first air?
---
A: 2011


Problem: Paper:

Its knowledge and uses spread from China through the Middle East to medieval Europe in the 13th century, where the first water powered paper mills were built. Because of paper's introduction to the West through the city of Baghdad, it was first called bagdatikos. In the 19th century, industrial manufacture greatly lowered its cost, enabling mass exchange of information and contributing to significant cultural shifts. In 1844, the Canadian inventor Charles Fenerty and the German F. G. Keller independently developed processes for pulping wood fibres.

 In which century did the process become less cheaper than before?
---
A: unanswerable


Problem: Circadian rhythm:

Studies by Nathaniel Kleitman in 1938 and by Derk-Jan Dijk and Charles Czeisler in the 1990s put human subjects on enforced 28-hour sleep–wake cycles, in constant dim light and with other time cues suppressed, for over a month. Because normal people cannot entrain to a 28-hour day in dim light if at all,[citation needed] this is referred to as a forced desynchrony protocol. Sleep and wake episodes are uncoupled from the endogenous circadian period of about 24.18 hours and researchers are allowed to assess the effects of circadian phase on aspects of sleep and wakefulness including sleep latency and other functions.[page needed]

What conditions were suppressed in the 28 hour wake-sleep cycle studies ?
---
A: time cues


Problem: Literature:

Definitions of literature have varied over time; it is a "culturally relative definition". In Western Europe prior to the eighteenth century, literature as a term indicated all books and writing. A more restricted sense of the term emerged during the Romantic period, in which it began to demarcate "imaginative" literature. Contemporary debates over what constitutes literature can be seen as returning to the older, more inclusive notion of what constitutes literature. Cultural studies, for instance, takes as its subject of analysis both popular and minority genres, in addition to canonical works.

During what literary movement did the definition of literature begin to narrow?
---
A:
the Romantic period