Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
Hydropower is produced in 150 countries, with the Asia-Pacific region generating 32 percent of global hydropower in 2010. China is the largest hydroelectricity producer, with 721 terawatt-hours of production in 2010, representing around 17 percent of domestic electricity use. There are now three hydroelectricity plants larger than 10 GW: the Three Gorges Dam in China, Itaipu Dam across the Brazil/Paraguay border, and Guri Dam in Venezuela. The cost of hydroelectricity is low, making it a competitive source of renewable electricity. The average cost of electricity from a hydro plant larger than 10 megawatts is 3 to 5 U.S. cents per kilowatt-hour.
 Which country is the smallest hydroelectricity producer?
A: unanswerable

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Examples of Ottoman architecture of the classical period, besides Istanbul and Edirne, can also be seen in Egypt, Eritrea, Tunisia, Algiers, the Balkans and Romania, where mosques, bridges, fountains and schools were built. The art of Ottoman decoration developed with a multitude of influences due to the wide ethnic range of the Ottoman Empire. The greatest of the court artists enriched the Ottoman Empire with many pluralistic artistic influences: such as mixing traditional Byzantine art with elements of Chinese art.
The ottoman empire built structures in Romania that included Mosques, and Bridges, what else was built?
A: fountains and schools

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In the United States, there was a movement to resettle American free blacks and freed slaves in Africa. The American Colonization Society was founded in 1816 in Washington, DC for this purpose, by a group of prominent politicians and slaveholders. But its membership grew to include mostly people who supported abolition of slavery. Slaveholders wanted to get free people of color out of the South, where they were thought to threaten the stability of the slave societies. Some abolitionists collaborated on relocation of free blacks, as they were discouraged by discrimination against them in the North and believed they would never be accepted in the larger society. Most African Americans, who were native-born by this time, wanted to improve conditions in the United States rather than emigrate. Leading activists in the North strongly opposed the ACS, but some free blacks were ready to try a different environment.
Who preferred to live in the North?
A: unanswerable

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New York City has focused on reducing its environmental impact and carbon footprint. Mass transit use in New York City is the highest in the United States. Also, by 2010, the city had 3,715 hybrid taxis and other clean diesel vehicles, representing around 28% of New York's taxi fleet in service, the most of any city in North America.
How many clean diesel and hybrid taxicabs did New York City have in 2010?
A:
3,715