In this task, you are given a question and a context passage. You have to answer the question based on the given passage.
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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 is Cork, Context: The climate of Cork, like the rest of Ireland, is mild and changeable with abundant rainfall and a lack of temperature extremes. Cork lies in plant Hardiness zone 9b. Met Éireann maintains a climatological weather station at Cork Airport, a few kilometres south of the city. It should be noted that the airport is at an altitude of 151 metres (495 ft) and temperatures can often differ by a few degrees between the airport and the city itself. There are also smaller synoptic weather stations at UCC and Clover Hill.

Answer: Ireland


Question: Why is Philadelphia a tourist attraction?, Context: The area's many universities and colleges make Philadelphia a top international study destination, as the city has evolved into an educational and economic hub. With a gross domestic product of $388 billion, Philadelphia ranks ninth among world cities and fourth in the nation. Philadelphia is the center of economic activity in Pennsylvania and is home to seven Fortune 1000 companies. The Philadelphia skyline is growing, with several nationally prominent skyscrapers. The city is known for its arts, culture, and history, attracting over 39 million domestic tourists in 2013. Philadelphia has more outdoor sculptures and murals than any other American city, and Fairmount Park is the largest landscaped urban park in the world. The 67 National Historic Landmarks in the city helped account for the $10 billion generated by tourism. Philadelphia is the birthplace of the United States Marine Corps, and is also the home of many U.S. firsts, including the first library (1731), first hospital (1751) and medical school (1765), first Capitol (1777), first stock exchange (1790), first zoo (1874), and first business school (1881). Philadelphia is the only World Heritage City in the United States.

Answer:
67 National Historic Landmarks in the city