Question: Which artist who contributed to R Kelly's "Double Up" album began his solo career in 2000 ?
Context: Chain Letter is the debut studio album by American singer-songwriter Brooke Valentine, released on March 15, 2005, by Virgin Records America.  Work on the album began after Valentine left the female group Best Kept Secret, in order to pursue a solo career.  She moved to Los Angeles, California with producer and Subliminal Entertainment CEO Deja the Great to begin work on the album.  Valentine enlisted a variety of producers to work on the album including Bink! , Bloodshy & Avant, Déjà "The Great", Jermaine Dupri, Brandon Howard, Lil Jon, Matt Serletic among others. Luke Calleja (born 3 July 1985), professionally known as Kronic is an Australian Artist, DJ, record producer, songwriter and remixer.  He is most known for producing and co-writing Lil Jon’s Bend Ova.  His remix and production credits includes records for Lady Gaga, Jennifer Lopez, R Kelly, Austin Mahone, Lil Jon, Pitbull, Enrique Iglesias and Nervo.  He released his debut EP "Sophisticated Ignorance" in 2016.  In 2017 his collaboration with Far East Movement and Savage, Push, was used in the trailer for the upcoming "The Fast And The Furious" film, which premiered to over 100 million viewers during the 2017 Super Bowl. Double Up is the eighth studio album by American R&B singer and songwriter R. Kelly.  It was released on May 29, 2007, by Jive Records, distributed by Zomba Label Group.  The album features the contributions with guest appearances and also the productions, which was handled by R. Kelly, alongside with Swizz Beatz, The Runners, Snoop Dogg, Khao, Nelly, Chamillionaire and Polow da Don. The Flying Burrito Bros is the third album by the country rock group, The Flying Burrito Brothers, released in the spring of 1971.  Before recording sessions for the album began, Gram Parsons departed from the band for a solo career, leaving Chris Hillman and "Sneaky" Pete Kleinow to carry on.  In Parsons' place, the band hired a young unknown musician named Rick Roberts, who later was the primary lead singer of Firefall.  Guitarist Bernie Leadon would also leave the band shortly after the album's release, going on to co-found the Eagles. Blowfly's Punk Rock Party is the 2006 album by Blowfly and his second release for Jello Biafra's label Alternative Tentacles.  On this album numerous classics of the punk rock genre by artists such as the Ramones and the Dead Kennedys are given the trademark Blowfly sex parody treatment, as well as one originally non-punk rock song parodied in punk style and several original songs.  Jello Biafra makes a guest appearance on both versions of "R Kelly In Cambodia" as does Raf Classic from the Crumbs on "Should I Fuck This Big Fat Ho?"  Six "clean" radio edits are also included. R&B Thug is a song by R&B singer R. Kelly on his fourth solo album TP-2. com in 2000.  It is the third song on the album and was never officially released as a single, but R. Kelly sang this song in an acceptance speech at the 27th annual AMA in 2000.  Jessica Simpson, Tyrese and Julio Iglesias Jr. presented the award for favorite soul/r&b artist.  R. Kelly won the award and did the a capella version of "R&B Thug" for his fans.  "R&B Thug" or "R&B Thing" is over four minutes long.  No music video has been made for this song but it is frequently incorporated in R. Kelly concerts. Double Dutchess is the second studio album by American singer Fergie.  It was released on September 22, 2017.  The album is the singer's first to be released under her own imprint, Dutchess Music, in a partnership with Retrofuture Productions and BMG Rights Management, and first since her solo debut, "The Dutchess" (2006).  Promotion for the album began with the release of the album's first single "L.A. Love (La La)" in late 2014. " M.I.L.F. $" was released as the second single from the album in July 2016, followed by the release of "Life Goes On" in November that same year. " You Already Know" featuring Nicki Minaj was released as the fourth single on September 12, 2017.  "Double Dutchess" received mixed reviews from music critics. Heart to Yours is the first solo album by American singer Michelle Williams.  Released on April 16, 2002 by Sanctuary and Columbia Records, it became the first solo release of any Destiny's Child member.  Production of the album began in 2001, with Williams working with an array of producers, including her brother Erron Williams (who produced the title track), HR Crump and Warryn Campbell.  "Heart to Yours" is primarily an urban contemporary gospel album, however it heavily incorporates elements of many other styles and genres such as neo-soul, inspirational, R&B and even rock music.  The album's lyrical content and subject matter is also diverse and ranges from songs that glorify and praise God to tributes dedicated to the victims of the September 11, 2001 attacks in the United States, which encourage those suffering in the aftermath of the attacks that the "sun will shine again". Double (stylized as DOUBLE) is the stage name for Japanese R&B singer Takako Hirasawa (平澤貴子 , Hirasawa Takako ) (born March 14, 1975).  Double used to be the name for the two member R&B group consisting of Takako and her sister Sachiko.  After the death of her sister in May 1999, Takako started her solo career adopting Double as her stage name.  Double has been titled as the "Queen of R&B" and is considered to be a pioneer for being the first artist to bring American-style R&B to Japan. Cornell Iral Haynes Jr. (born November 2, 1974), known professionally as Nelly, is an American rapper, singer, songwriter, entrepreneur, investor, and occasional actor from St. Louis, Missouri.  Nelly embarked on his music career with Midwest hip hop group St. Lunatics, in 1993 and signed to Universal Records in 1999.  Under Universal, Nelly began his solo career in the year 2000, with his debut album "Country Grammar", of which the title-track was a top ten hit.  The album debuted at number three on the "Billboard" 200 and went on to peak at number one.  "Country Grammar" is Nelly's best-selling album to date, selling over 8.4 million copies in the United States.  His following album "Nellyville", produced the number-one hits "Hot in Herre" and "Dilemma" (featuring Kelly Rowland).  Other singles included "Work It" (featuring Justin Timberlake), "Air Force Ones" (featuring Murphy Lee and St. Lunatics), "Pimp Juice" and "#1".
Answer: Nelly