instruction:
In this task, you are given a question and a context passage. You have to answer the question based on the given passage.
question:
Which has more prestige, the Spring Cup Series or low-tier NASCAR circuits?, Context: In addition to professional team sports, North Carolina has a strong affiliation with NASCAR and stock-car racing, with Charlotte Motor Speedway in Concord hosting two Sprint Cup Series races every year. Charlotte also hosts the NASCAR Hall of Fame, while Concord is the home of several top-flight racing teams, including Hendrick Motorsports, Roush Fenway Racing, Richard Petty Motorsports, Stewart-Haas Racing, and Chip Ganassi Racing. Numerous other tracks around North Carolina host races from low-tier NASCAR circuits as well.
answer:
Sprint Cup Series


question:
The expansion of what further cemented Houston's emergence as a powerhouse commercial city?, Context: By 1860, Houston had emerged as a commercial and railroad hub for the export of cotton. Railroad spurs from the Texas inland converged in Houston, where they met rail lines to the ports of Galveston and Beaumont. During the American Civil War, Houston served as a headquarters for General John Bankhead Magruder, who used the city as an organization point for the Battle of Galveston. After the Civil War, Houston businessmen initiated efforts to widen the city's extensive system of bayous so the city could accept more commerce between downtown and the nearby port of Galveston. By 1890, Houston was the railroad center of Texas.
answer:
bayous


question:
Where did Greece's green electricity sources come from?, Context: In 2008 renewable energy accounted for 8% of the country's total energy consumption, a rise from the 7.2% it accounted for in 2006, but still below the EU average of 10% in 2008. 10% of the country's renewable energy comes from solar power, while most comes from biomass and waste recycling. In line with the European Commission's Directive on Renewable Energy, Greece aims to get 18% of its energy from renewable sources by 2020. In 2013 and for several months, Greece produced more than 20% of its electricity from renewable energy sources and hydroelectric power plants. Greece currently does not have any nuclear power plants in operation, however in 2009 the Academy of Athens suggested that research in the possibility of Greek nuclear power plants begin.
answer:

renewable energy sources and hydroelectric power plants


