Question: Which singer was the leader of an alternative rock band,  Bob Mould or Hayley Williams?

full_context: Document 1: Black Sheets of Rain: Black Sheets of Rain is the second solo album by former Hüsker Dü guitarist and singer Bob Mould and features the Modern Rock Top 10 hit "It's Too Late." The album was a return to a heavier sound following his folk influenced solo debut, "Workbook". Bassist Tony Maimone and drummer Anton Fier, both veterans of Pere Ubu, once again served as Mould's rhythm section.
Document 2: Paramore (album): Paramore is the self-titled fourth studio album by American rock band Paramore. It was released on April 5, 2013, through Fueled by Ramen as a follow-up to "Brand New Eyes" (2009). It is their first full-length album released after the departure of co-founders Josh and Zac Farro in 2010. Recorded between April and November 1, 2012, the album was described by the band as being a "statement" and a reintroduction of the band to the world and to themselves. It is the only album without Zac Farro on drums, and the final album recorded with bassist Jeremy Davis before he left the band in 2015.
Document 3: Bob Mould: Robert Arthur Mould (born October 16, 1960) is an American musician, principally known for his work as guitarist, vocalist and songwriter for alternative rock bands Hüsker Dü in the 1980s and Sugar in the 1990s.
Document 4: Paramore discography: The American rock band Paramore has released five studio albums, three extended plays, two live albums, eighteen singles, one video album, and nineteen music videos. The band was formed in Franklin, Tennessee, in 2004 by lead vocalist Hayley Williams with guitarists Josh Farro and Taylor York, bassist Jeremy Davis, and drummer Zac Farro. In 2005, Paramore signed with the New York City-based Fueled by Ramen and released their debut album entitled "All We Know Is Falling". Three singles were released from the album, but none of them charted. The album did not chart in the "Billboard" 200 either, although it peaked at number thirty in the "Billboard" Top Heatseekers. "All We Know Is Falling" received Gold certification in the United Kingdom and in July 2014 the RIAA certified the album Gold in the United States.
Document 5: Bob Mould (album): Bob Mould (sometimes referred to as Hubcap) is the third solo album by former Hüsker Dü and Sugar guitarist and singer Bob Mould. It was recorded and mixed between September & November 1995 and released in April 1996. Mould played all of the instruments on the album himself, and the sleeve notes declare, "This one is for me." In the place of traditional band credits, the sleeve states, "Bob Mould is Bob Mould."
Document 6: Silver Age (album): Silver Age is the tenth solo album from former Hüsker Dü and Sugar frontman Bob Mould. Mould was joined on bass by Jason Narducy and on drums by Superchunk's Jon Wurster.
Document 7: Zac Farro: Zachary Wayne "Zac" Farro (born June 4, 1990) is an American musician and drummer of the rock band Paramore. He is also the younger brother of Josh Farro, who is Paramore's former lead guitarist and backing vocalist. After he and his brother exited Paramore in 2010, Josh formed a band named Novel American, which Zac was also a part of. Zac is currently the sole member of the band HalfNoise. Farro rejoined Paramore on February 2, 2017.
Document 8: List of songs recorded by Paramore: American rock band Paramore have recorded songs for five studio albums, a box set, an extended play and two soundtrack albums. In 2002, at age 13, vocalist Hayley Williams moved to Franklin, Tennessee, where she met brothers Josh Farro and Zac Farro. The band was officially formed by Josh Farro (lead guitar and backing vocals), Zac Farro (drums), Jeremy Davis (bass guitar) and Williams (lead vocals) in 2004, with the later addition of Williams' neighbor Jason Bynum (rhythm guitar). In 2005, Paramore signed with the New York City-based Fueled by Ramen and released their debut album entitled "All We Know Is Falling" that year. Three singles were released to promote the album.
Document 9: Workbook (album): Workbook is the 1989 debut solo album by American guitarist and singer Bob Mould, following the breakup of the influential rock band Hüsker Dü. The album has a strong folk influence and lighter overall sound than he had been known for up to that point, although heavy guitar still features occasionally. Drummer Anton Fier and bassist Tony Maimone, both of Pere Ubu fame, served as Mould's rhythm section on the album and on the subsequent live shows. The single "See a Little Light" was a hit on the US Modern Rock chart.
Document 10: Hayley Williams: Hayley Nichole Williams (born December 27, 1988) is an American singer, songwriter and musician. She serves as the lead vocalist, primary songwriter and occasional keyboardist of the rock band Paramore. The band was formed in 2004 by Josh Farro, Zac Farro, Jeremy Davis and Williams. The band consists of Hayley Williams, Zac Farro and Taylor York. The band has five studio albums: "All We Know Is Falling" (2005), "Riot!" (2007), "Brand New Eyes" (2009), "Paramore" (2013) and "After Laughter" (2017).
Document 11: Circle of Friends (Bob Mould video): Circle of Friends is a DVD by Bob Mould of a live concert recorded in 2005 at the in Washington, D.C. The performance included songs from Mould's earlier bands Hüsker Dü and Sugar, as well as his solo work. This particular show was part of the "Body of Song" tour, Mould's first non-solo tour for over a decade and the first one in which Hüsker Dü material was played in a band format since the band broke up in 1988.
Document 12: Hard Times (Paramore song): "Hard Times" is a song by American rock band Paramore from their fifth studio album "After Laughter". It was released on April 19, 2017 through Fueled by Ramen as the album's lead single. The song was written by lead vocalist Hayley Williams and guitarist Taylor York and was recorded in the band's hometown, Nashville, Tennessee. It is the first single to be released by the band since the return of drummer Zac Farro and the departure of former bassist Jeremy Davis.
Document 13: Paramore: Paramore is an American rock band from Franklin, Tennessee, formed in 2004. The band currently consists of lead vocalist Hayley Williams, guitarist Taylor York and drummer Zac Farro.
Document 14: Hüsker Dü: Hüsker Dü was an American rock band formed in Saint Paul, Minnesota, in 1979. The band's continual members were guitarist/vocalist Bob Mould, bassist Greg Norton, and drummer/vocalist Grant Hart. Hüsker Dü first gained notability as a hardcore punk band, later crossing over into alternative rock. Mould and Hart were the principal songwriters for Hüsker Dü, with Hart's higher-pitched vocals and Mould's baritone taking the lead in alternating songs.
Document 15: Sugar (American band): Sugar was an American alternative rock band of the early 1990s. Formed in 1992, they were led by the singer and guitarist Bob Mould (ex-Hüsker Dü), alongside bassist David Barbe (ex-Mercyland) and drummer Malcolm Travis (ex-Human Sexual Response).
ground_truth: Robert Arthur Mould