Question: "Free as a Bird" is a song originally composed and recorded in 1977 as a home demo by John Lennon. In 1995, a studio version of the recording, incorporating contributions from Paul McCartney, George Harrison and Ringo Starr, was released as a single by the Beatles. It was released 25 years after the break-up of the band and 15 years after the death of Lennon. The single was released as part of the promotion for The Beatles Anthology video documentary and the band's Anthology 1 compilation album.

George Martin, who had produced most of the Beatles' 1960s recordings, turned down an invitation to produce "Free as a Bird" due to hearing problems (though he subsequently managed to produce and direct the Anthology series). Harrison, in turn, suggested Lynne as producer (co-producer of his 1987 album, Cloud Nine) and work commenced at McCartney's studio in February 1994. Geoff Emerick and Jon Jacobs were chosen to engineer the new tracks.  The original 1977 tape of Lennon singing the song was recorded on a mono cassette, with vocals and piano on the same track. They were impossible to separate, so Lynne had to produce the track with voice and piano together, but commented that it was good for the integrity of the project, as Lennon was not only singing occasional lines, but also playing on the song.  Although Lennon had died in 1980, Starr said that the three remaining Beatles agreed they would pretend that Lennon had "gone for lunch", or had gone for a "cup of tea". The remaining Beatles recorded a track around Lennon's basic song idea, but which had gaps they had to fill in musically. Some chords were changed, and the arrangement was expanded to include breaks for McCartney and Harrison to sing extra lines. Harrison played slide guitar in the solo.  The Beatles' overdubs and production were recorded between February and March 1994 in Sussex, England, at McCartney's home studio. It ends with a slight coda including a strummed ukulele by Harrison (an instrument he was known to have played often) and the voice of John Lennon played backwards. The message, when played in reverse, is "Turned out nice again", which was the catchphrase of George Formby. The final result sounds like "made by John Lennon", which, according to McCartney, was unintentional and was only discovered after the surviving Beatles reviewed the final mix. When Starr heard McCartney and Harrison singing the harmonies, and later the finished song, he said that it sounded just like them [the Beatles]. He explained his comment by saying that he looked at the project as "an outsider". Lynne fully expected the finished track to sound like the Beatles, as that was his premise for the project, but Harrison added: "It's gonna sound like them if it is them... It sounds like them now."  McCartney, Harrison and Starr all agreed that the recording process was more pleasurable than when they later recorded "Real Love" (the second song chosen for release); as it was almost finished, they had very little input, and felt like sidemen for Lennon.

Using a quote from the above article, answer the following question: What were their roles in the song?
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Answer: chosen to engineer the new tracks.

Problem: Christina Maria Aguilera (born December 18, 1980) is an American singer, songwriter, actress, reality show personality and television personality. Born in Staten Island, New York and raised in Rochester and Wexford, Pennsylvania, she appeared on the television series Star Search and The Mickey Mouse Club in her early years. After recording "Reflection", the theme for Disney's 1998 film Mulan, Aguilera signed with RCA Records. She rose to prominence with her 1999 self-titled debut album that spawned the US Billboard Hot 100 number-one singles "Genie in a Bottle", "What a Girl Wants", and "Come On Over Baby

When planning her fourth studio album, Aguilera leaned towards a new artistic direction that she felt had more musical and lyrical depth. She named the album Stripped and explained that the title represented "a new beginning, a re-introduction of [herself] as a new artist in a way". For the album, Aguilera served as executive producer and co-wrote most of the songs. The album was preceded by the single "Dirrty", which was released to shed Aguilera's teen pop image and express her sexuality and aggression. Its accompanying music video generated controversy for depicting various sexual fetishes and concepts. Aguilera's new image presented in the video started to overshadow her music, generating widespread criticism from both her peers including Shakira and Jessica Simpson and the public. Aguilera defended her new image, explaining that "I'm in the power position, in complete command of everything and everybody around me. To be totally balls-out like that is, for me, the measure of a true artist."  The final cut of Stripped incorporated various genres from flamenco and R&B to rock and lyrically revolved around the theme of self-esteem while also discussing sex and gender equality. It was released in October 2002 to mixed critical reviews; Jancee Dunn from the Rolling Stone praised Aguilera's vocals yet panned the album for its lack of musical concentration. The album was nonetheless a commercial success, peaking at number two on the Billboard 200 and has sold over 4.3 million copies in the United States. It was a major success in the United Kingdom, having sold 2 million copies and became the second highest-selling album by a female US artist of the 2000s decade, behind Norah Jones with Come Away with Me. Stripped has sold over 12 million copies worldwide. The album was followed by four singles, "Beautiful", "Fighter", "Can't Hold Us Down", and "The Voice Within". "Beautiful" received universal acclaim for positive portrayal of the LGBT community and was the album's most commercially successful single, peaking at number two on the Billboard Hot 100. It earned Aguilera a Grammy Award for Best Female Pop Vocal Performance at the 2004 ceremony. The song was later listed at number 52 among the 100 Best Songs of the 2000s by the Rolling Stone in 2011.  During the promotion of Stripped, Aguilera cultivated a new image by adopting the alter ego Xtina, dyeing her hair black, and debuting several tattoos and piercings. She co-headlined the Justified and Stripped Tour alongside Justin Timberlake from June to September 2003 in support of Stripped and Timberlake's album Justified, before embarking on her solo The Stripped Tour until December. Aguilera garnered media attention after attending the 2003 MTV Video Music Awards in August, where she and Britney Spears kissed Madonna during their performance of "Like a Virgin" and "Hollywood". Later that year, she was the host of the 2003 MTV Europe Music Awards, where she won an award for Best Female. Billboard also announced Aguilera as the Top Female Pop Act of 2003.

What is Stripped?

Answer with quotes:
her fourth studio album,