Question: The sponsor of the 2007 NRL season is Australia's largest what?

full_context: Document 1: 2017 AFL season: The 2017 Australian Football League season was the 121st season of the elite Australian rules football competition. There are 18 teams competing in the league, the same as the previous five seasons. The first game was played on Thursday, 23 March, and the season concluded with the 2017 AFL Grand Final on Saturday, 30 September.
Document 2: Telstra: Telstra Corporation Ltd. (known as Telstra) is an Australian telecommunications and media company which builds and operates telecommunications networks and markets voice, mobile, internet access, pay television and other entertainment products and services. Telstra is Australia's largest telecommunications company.
Document 3: Telstra Tower: Telstra Tower (also known as Black Mountain Tower and formerly Telecom Tower) is a telecommunications tower and lookout that is situated above the summit of Black Mountain in Australia's capital city of Canberra. It is named after Australia's largest telecommunications company, Telstra Corporation. Rising 195.2 m above the mountain summit, it is a landmark in Canberra and offers panoramic views of the city and its surrounding countryside from an indoor observation deck and two outdoor viewing platforms.
Document 4: Comcast: Comcast Corporation (formerly registered as Comcast Holdings) is an American global telecommunications conglomerate that is the largest broadcasting and cable television company in the world by revenue. It is the second-largest pay-TV company after AT&T, largest cable TV company and largest home Internet service provider in the United States, and the nation's third-largest home telephone service provider. Comcast services U.S. residential and commercial customers in 40 states and in the District of Columbia. The company's headquarters are located in Philadelphia, Pennsylvania. As the owner of the international media company NBCUniversal since 2011, Comcast is a producer of feature films and television programs intended for theatrical exhibition and over-the-air and cable television broadcast.
Document 5: Ptcl: Pakistan Telecommunication Company Limited (PTCL) is the leading telecommunication company in Pakistan. The company provides telephonic and Internet services nationwide and is the backbone for the country's telecommunication infrastructure despite the arrival of a dozen other telecommunication corporations, including Telenor Corps and China Mobile Ltd. The corporation manages and operates around 2000 telephone exchanges across the country, providing the largest fixed-line network. Data and backbone services such as GSM, HSPA+, CDMA, LTE, broadband Internet, IPTV, and wholesale are an increasing part of its business.
Document 6: Sydney Roosters: The Sydney Roosters are an Australian professional rugby league football club based in the Eastern Suburbs of Sydney. The club competes in the National Rugby League (NRL) competition and is one of the oldest clubs in Australian rugby league history, having won thirteen New South Wales Rugby League (NSWRL) and National Rugby League titles, and several other competitions. Only the South Sydney Rabbitohs and the St. George Dragons have won more premierships. The club holds the record for having the most wins and the second greatest margin of victory in a match in Australian rugby league history. The Eastern Suburbs DRLFC is the only club to have played in each and every season at the elite level, and since the 1970s has often been dubbed the "glamour club" of the league. Coached by Trent Robinson along with captains Boyd Cordner and Jake Friend, the Roosters play their home games at the Sydney Football Stadium.
Document 7: Optus: Singtel Optus Pty Limited is the second largest telecommunications company in Australia. It is a wholly owned subsidiary of SingTel (a company headquartered in Singapore) since 2001. The company primarily trades under the Optus brand, while maintaining several wholly owned subsidiary brands, such as Virgin Mobile Australia in the mobile telephony market, Uecomm in the network services market and Alphawest in the ICT services sector.
Document 8: Tanzania Telecommunications Company Limited: Tanzania Telecommunications Company Limited (TTCL) is the oldest and largest fixed line telecommunications company in Tanzania. The company comes forth from the former Tanzania Posts and Telecommunications Corporation in 1993. TTCL was wholly owned by the Government of Tanzania until the partial privatisation of the company on 23 February 2001.
Document 9: 2007 NRL Grand Final: The 2007 NRL Grand Final was the conclusive, premiership-deciding match of the 2007 NRL season. It was played between the first-placed Melbourne Storm and second-placed Manly Warringah Sea Eagles at Telstra Stadium on 30 September, in front of 81,392 spectators. The 2007 Grand final was the fourth to be played between the first and second placed teams, and the first in three years. The match was the last Grand Final played at night until 2013; each Grand Final in the intervention switched to a 5:00pm AEST kick-off. This match was also the most-watched television program on Australian TV for 2007.
Document 10: 2007 NRL season: The 2007 NRL season was the one hundredth season of professional rugby league football club competition in Australia, and the tenth run by the National Rugby League. Sixteen teams contested the NRL's 2007 Telstra Premiership, and with the inclusion of a new team, the Gold Coast Titans, the competition was the largest run since the 1999 NRL season.
Document 11: Melbourne Storm: Melbourne Storm is a rugby league team based in Melbourne, Victoria, that participates in the National Rugby League. The first fully professional rugby league team based in the state, they entered the competition in 1998. Melbourne Storm was originally a Super League initiative and created in 1997 during the Super League war. The club plays its home games at AAMI Park. The Storm has won three premierships since its inception, in 1999, 2012 and 2017 and has contested several more grand finals. The Storm won two additional premierships, in 2007 and 2009, but these titles were stripped by the NRL following the discovery of a salary cap breach in 2010, which is against the rules of the NRL. Melbourne Storm also competed in the NRL's Under-20s competition (as Melbourne Thunderbolts) from 2008 until its demise in 2017. In addition, the club has also expanded into netball with a joint venture with University of the Sunshine Coast. The Sunshine Coast Lightning commenced playing in the National Netball League in 2017.
Document 12: 2012 NRL season: The 2012 NRL season was the 105th season of professional rugby league club competition in Australia, and the first run by the newly formed Australian Rugby League Commission. The main competition, called the 2012 NRL Telstra Premiership due to sponsorship from Telstra Corporation was contested by the sixteen teams of the National Rugby League. The season started with the 2012 NRL All Stars match and culminated in the 2012 NRL grand final. The 2012 Toyota Cup season also took place alongside the Premiership. The McIntyre Final Eight System, in use since 1999, was replaced with the finals system previously used by the ARL in the 1990s.
Document 13: 1998 NRL season: The 1998 NRL season was the 91st season of professional rugby league football in Australia, and the inaugural season of the newly formed National Rugby League (NRL). After the 1997 season, in which the Australian Rugby League and Super League organisations ran separate competitions parallel to each other, they joined to create a reunited competition in the NRL. The first professional rugby league club to be based in Victoria, the Melbourne Storm was introduced into the League, and with the closure of the Hunter Mariners, Western Reds and South Queensland Crushers, twenty teams competed for the premiership, which culminated in the 1998 NRL grand final between the Brisbane Broncos and Canterbury Bulldogs.
Document 14: 2007 NRL season results: The 2007 NRL season consisted of 25 weekly regular season rounds, starting from 16 March and ending on 2 September, followed by four weeks of play-offs that culminated in a grand final on 30 September.
Document 15: AT&amp;T: AT&T Inc. is an American multinational telecommunications conglomerate, headquartered at Whitacre Tower in downtown Dallas, Texas. AT&T is the world's largest telecommunications company. AT&T is the second largest provider of mobile telephone services and the largest provider of fixed telephone services in the United States, and also provides broadband subscription television services through DirecTV; combined with AT&T's legacy U-verse service, this also makes AT&T the largest pay television operator. AT&T is the second-largest company in Texas, behind ExxonMobil. s of February 2017 , AT&T is the 12th largest company in the world (non-oil and overall) as measured by a composite of revenues, profits, assets and market valuation. AT&T is the largest telecommunications company in the world by revenue. s of 2017 , it is also the 18th-largest mobile telecom operator in the world, with 134 million mobile customers. AT&T was ranked at #4 on the 2017 rankings of the world's most valuable brands published by Brand Finance.
ground_truth: telecommunications company