Background: Gregory LeNoir Allman was born at Saint Thomas Hospital on December 8, 1947 in Nashville, Tennessee, to Willis Turner Allman (1918-1949) and Geraldine Robbins Allman (1917-2015). The couple had met during World War II in Raleigh, North Carolina, when Allman was on leave from the U.S. Army, and were later married. Their first child, Duane Allman, was born in Nashville in 1946. On December 26, 1949, Willis offered a hitchhiker a ride home and was subsequently shot and killed in Norfolk, Virginia.
Context: Allman moved to Richmond Hill, Georgia, in 2000, purchasing five acres on the Belfast River. The last incarnation of the Allman Brothers Band was well-regarded among fans and the general public, and remained stable and productive. The band released their final studio album, Hittin' the Note (2003), to critical acclaim. Allman co-wrote many songs on the record with Haynes, and he regarded it as his favorite album by the group since their earliest days. The band continued to tour throughout the 2000s, remaining a top touring act, regularly attracting more than 20,000 fans. The decade closed with a successful fortieth anniversary celebration at the Beacon Theater, where the band would hold residencies most years during their reunion. In 2014, the Allman Brothers Band performed their final concerts, as Haynes and Derek Trucks desired to depart the group.  Allman struggled with health problems during the last years of his life. He was diagnosed with hepatitis C in 2007, which he attributed to a dirty tattoo needle. By the next year, they had discovered three tumors within his liver. He went on a waiting list and after five months, he underwent a successful liver transplant in 2010.  In 2011, Allman went public about his battle with hepatitis C. He headlined Merck and the American Liver Foundation's "Tune In to Hep C Campaign" to raise awareness and urge baby boomers to get tested and treated. As part of Tune In to Hep C, The Allman Brothers Band headlined a hepatitis C fundraiser and awareness concert at the Beacon Theater in New York. The concert raised $250,000 to benefit the National Viral Hepatitis Roundtable and the American Liver Foundation for education and awareness efforts. The National Viral Hepatitis Roundtable in October 2017 created the Gregg Allman Hepatitis C Leadership Award - an annual award to posthumously honor Allman and others who work on behalf of people living with hepatitis C. Michael Lehman, Allman's longtime manager, accepted the award on his behalf.  Allman's seventh album, Low Country Blues, was produced by T-Bone Burnett. Upon its release in January 2011, it represented Allman's highest-ever chart peak in the U.S., debuting at number five. He promoted the album heavily in Europe, until he had to cancel the rest of the trip due to an upper respiratory infection. This led to lung surgery later in 2011, and rehab in 2012 for addiction following his treatments. That year, Allman released his memoir, My Cross to Bear, which was thirty years in the making. In 2014, a tribute concert was held celebrating his career; it was later released as All My Friends: Celebrating the Songs & Voice of Gregg Allman.
Question: What health problems existed
Answer: He was diagnosed with hepatitis C in 2007, which he attributed to a dirty tattoo needle. By the next year, they had discovered three tumors

Background: Gwen Renee Stefani (; born October 3, 1969) is an American singer, songwriter, fashion designer, and actress. She is a co-founder and the lead vocalist of the band No Doubt that experienced major success after their breakthrough studio album Tragic Kingdom (1995) along with various successful singles, including "Just a Girl"
Context: Throughout her career as a solo artist, Stefani has won several music awards, including one Grammy Award, four MTV Video Music Awards, one American Music Award, one Brit Award, and two Billboard Music Awards. With No Doubt, she has won two Grammy Awards. In 2005, Rolling Stone called her "the only true female rock star left on radio or MTV" and featured her on the magazine's cover. Stefani received the Style Icon Award at the first People Magazine Awards in 2014. Additionally in 2016, the singer was honored at the Radio Disney Music Awards with a Hero Award, which is given to artists based on their personal contributions to various charitable works.  Stefani has been referred to as a "Pop Princess" by several contemporary music critics. In 2012, VH1 listed the singer at the number thirteen on their list of "100 Greatest Women in Music". Stefani's work has influenced a number of artists and musicians including Hayley Williams of Paramore, Best Coast, Katy Perry, Kesha, Marina and the Diamonds, Stefy, Rita Ora, Sky Ferreira, and Cover Drive. The latter group, a quartet of Barbados musicians, claimed that both Stefani and No Doubt had helped influence their music, to which the lead singer of the group, Amanda Reifer, admitted that she would "pass out" if she were to ever meet Stefani.  The lead single from Love. Angel. Music. Baby., "What You Waiting For?", was considered by Pitchfork to be one of the best singles by Stefani, and would later place it at number sixteen on their "Top 50 Singles of 2004" list. Additionally, "Hollaback Girl" from the aforementioned album would go on to be the first song to digitally sell an excess of one million copies in the United States; it was certified platinum in both the United States and Australia, and peak at number forty-one on Billboard's decade-end charts for 2000-09. Since its release in 2005, "Hollaback Girl" has been called Stefani's "signature song" by Rolling Stone.
Question: What is one of her hit songs?
Answer:
Hollaback Girl"