Question: The suburb that contains the Williamstown Lighthouse is how many kilometers southwest of Melbourne's central business district? 

Context paragraphs:
New Canal Light: The New Canal Light or (more commonly New Canal Lighthouse or New Basin Canal Lighthouse) was first established in 1838 at the north end of the New Basin Canal which ran from Lake Pontchartrain to the Uptown or "American" section of the city which today is known as the New Orleans Central Business District.  The canal was filled in about 1950, but the lighthouse remained on a jetty extending into the lake on a half mile long stretch of the canal that was left and is still used as a small boat and yachting harbor.

Williamstown North, Victoria: Williamstown North is a suburb of Melbourne, Victoria, Australia, 7 km south-west of Melbourne's central business district.  Its local government area is the City of Hobsons Bay.  At the 2011 census , Williamstown North had a population of 1,544.

Downtown McAllen: Downtown McAllen is the main business district in McAllen, Texas.  U.S. Interstate 2 runs directly south of the downtown area.  The City's Central Business District and encompasses the area west of 10th street, east of Bicentennical, south of Hackberry and north of Interstate 2.  This area thrives from over 250 retail businesses, the Federal building Bentsen tower, McAllen city Hall, the Mexican Consulate, the Honduran Consulate, the Guatemalan Consulate, Medical offices, banks, the City's Bus Terminal McAllen Central Station and Downtown Parking Garage.  It is estimated that 5,516,000 pedestrians visit the Central Business District.  The two tallest towers in the area are the Chase Tower and the Bentson Tower.  17th Street in Downtown is lined with many bars, pubs, lounges, restaurants, and music venues.  It is also home to the historic Cine El Rey.

Williamstown Lighthouse: The Williamstown Lighthouse is situated at Point Gellibrand, in the Melbourne suburb of Williamstown.

North Melbourne railway station: North Melbourne railway station is located on the northern edge of the central business district of Melbourne, Australia.  The station is a major interchange point with the Craigieburn, Flemington Racecourse, Sunbury, Upfield, Werribee and Williamstown lines all servicing the station.  It opened on 6 October 1859.  It is listed on the Victorian Heritage Register.

Williamstown, Victoria: Williamstown is a suburb of Melbourne, Victoria, Australia, 9 km south-west of Melbourne's central business district in the local government area of the City of Hobsons Bay.

Sea Point: Sea Point (Afrikaans: "Seepunt") is one of Cape Town's most affluent and densely populated suburbs, situated between Signal Hill and the Atlantic Ocean, a few kilometres to the west of Cape Town's Central Business District (CBD).  Moving from Sea Point to the CBD, one passes through first the small suburb of Three Anchor Bay, then Green Point.  Seaward from Green Point is the area known as Mouille Point (pronounced MOO-lee), where the local lighthouse is situated.  It is neighboured to the southwest by the suburb of Bantry Bay.

Fortitude Valley, Queensland: Fortitude Valley (also known simply as "The Valley") is a suburb of central Brisbane, the state capital of Queensland, Australia.  The suburb lies immediately northeast of the Brisbane central business district, and is one of the hubs of Brisbane's nightlife, renowned for its nightclubs, bars and adult entertainment.  At the 2011 Australian Census Fortitude Valley recorded a population of 5,615.  In the 1950s, the suburb was the largest shopping precinct outside of a central business district in Australia.

Southbank, Victoria: Southbank is an inner urban neighbourhood of Melbourne, Victoria, Australia, 1 km south of Melbourne's central business district.  Its local government area are the Cities of Melbourne and Port Phillip.  At the 2011 Census, Southbank had a population of 11,235.  Its northernmost area is considered part of the Central Business District and Central Activities District of the City.  Southbank is bordered to the north by the Yarra River, and to the east by St Kilda Road.  Southbank's southern and western borders are bounded by Dorcas Street, Kings Way, the West Gate Freeway and Montague Street.

Altona North, Victoria: Altona North is a suburb of Melbourne, Victoria, Australia, 10 km south-west of Melbourne's Central Business District, located within the City of Hobsons Bay local government area.  Altona North recorded a population of 12,152 at the 2016 census .  Bordering suburbs include Altona, Brooklyn, Laverton North, Newport, South Kingsville, Williamstown North, Yarraville.  In addition to Paisley Park sporting complex, Altona North is home to three parks, S J Clement Reserve - Gilligan Rd, W L J Crofts Reserve - Blackshaws Rd, Urban Forest Reserve - Grieve Pde.

Supporting paragraphs: Williamstown Lighthouse Williamstown, Victoria
Answer: 9