Question: What city has its council offices in the suburb of Sturt and contains part of O'Halloran Hill, South Australia?

Context paragraphs:
O'Halloran Hill, South Australia: O'Halloran Hill is a suburb in the south of Adelaide, South Australia, situated on the hills south of the O'Halloran Hill Escarpment, which rises from the Adelaide Plains and located 18 km from the city centre via the Main South Road.  The suburb is split between the Cities of Marion and Onkaparinga, and it neighbours Happy Valley, Hallett Cove, Trott Park and Darlington.

O'Halloran Hill Recreation Park: O’Halloran Hill Recreation Park is a protected area located about 16 km south of the Adelaide city centre in the suburbs of Seaview Downs and O’Halloran Hill.  The recreation park was proclaimed under the "National Parks and Wildlife Act 1972" in 1989 for "recreation and nature conservation purposes" in respect to parcels of land acquired by the Government of South Australia starting in the 1970s for three purposes - creation of "an open space buffer", provision of "both visual amenity and recreational opportunities for the rapidly growing southern suburbs" and the creation of "a second ring of parklands around Adelaide that would cater for outdoor pursuits, as well as protecting the Hills Face Zone from development".  The recreation park is classified as an IUCN Category III protected area.

Northern Areas Council: Northern Areas Council is a local government area in the Yorke and Mid North region of South Australia.  The council seat and main council offices are at Jamestown, while the council also maintains district offices at Gladstone and Spalding.

Electoral district of Broken Hill: Broken Hill was an electoral district of the Legislative Assembly in the Australian state of New South Wales.  From 1894 to 1913, the Broken Hill district was covered by the electoral districts of "Broken Hill", Willyama and Sturt.  In the 1912 redistribution, the electoral district of "Broken Hill" was abolished and absorbed into "Willyama" and "Sturt".  In 1920, "Willyama", "Sturt" and the electoral district of Cobar were combined to create a three-member "Sturt".  In 1927, single-member electorates were recreated and the city of Broken Hill was split between "Sturt" and Murray.  From 1932, the city of Broken Hill was split between "Sturt" and Cobar.  In 1968 "Sturt" was renamed Broken Hill and included all of the city of Broken Hill.  In 1999, it was merged with part of "Murray" and renamed the electoral district of Murray-Darling.

District Council of Caltowie: The District Council of Caltowie was a local government area in South Australia, centred on the town and surrounding cadastral hundred of Caltowie.  It came into operation on 28 February 1878, with the first five councillors appointed by proclamation.  The town and hundred had both been laid out in 1872.  The council initially met in local hotels, leased private offices for a period, and met at Hornsdale Station for a year, before constructing purpose-built council offices in Charles Street, Caltowie, in 1896.

Electoral district of Davenport: Davenport is an electoral district of the House of Assembly in the Australian state of South Australia.  It is named after nineteenth-century pioneer and politician Sir Samuel Davenport.  Davenport is a 49.1 km² electorate covering part of outer suburban Adelaide and the southern foothills of the Adelaide Hills.  It takes in the suburbs of Bedford Park, Bellevue Heights, Blackwood, Craigburn Farm, Coromandel Valley, Eden Hills, Flagstaff Hill, Glenalta and Hawthorndene, as well as parts of Belair, Darlington, O'Halloran Hill and Upper Sturt.

Electoral district of Fisher: Fisher is an electoral district of the House of Assembly in the Australian state of South Australia.  It is named after James Fisher, a colonial politician and the first mayor of Adelaide.  It covers a 94.2 km² suburban and semi rural area on the southern fringes of Adelaide, taking in the suburbs of Aberfoyle Park, Chandlers Hill, Cherry Gardens, Coromandel East, Happy Valley, Reynella East and parts of Clarendon, O'Halloran Hill and Woodcroft.

Electoral district of Mitchell (South Australia): Mitchell is an electoral district of the House of Assembly in the state of South Australia.  It was first created in the redistribution of 1969, taking effect at the 1970 election.  Mitchell is named after philosopher Sir William Mitchell.  Mitchell is located in inner-south western Adelaide, covering 26.8 km² and encompassing the suburbs of Dover Gardens, Old Reynella, Reynella, Seacombe Gardens, Seacombe Heights, Seaview Downs, Sheidow Park, Sturt and Trott Park and parts of Darlington, O'Halloran Hill, Oaklands Park and Warradale.  The suburbs contained within the seat in 2010 were completely different as recently as 1989.  The 1989 seat centered on Park Holme, north-east of the current incarnation of Mitchell, where much of the seat of Elder is.  The 1989 boundary bordered the 2010 boundary in the south-west and north-east respectively.

Seaview Downs, South Australia: Seaview Downs is a suburb of Adelaide in the City of Marion.  The southern part of the suburb contains the O'Halloran Hill Recreation Park.

City of Marion: The City of Marion is a local government area in part of the southern and western suburbs of Adelaide, South Australia.  The council offices are in the suburb of Sturt.

Supporting paragraphs: O'Halloran Hill, South Australia City of Marion
Answer: City of Marion