Given the following context:  Audioslave's history dates back to October 18, 2000, when Rage Against the Machine's lead vocalist Zack de la Rocha announced he was leaving the band, citing a breakdown in its "decision-making process". Rage Against the Machine broke up as a result of de la Rocha's departure, but the remaining three members of the band—Tim Commerford, Tom Morello, and Brad Wilk—decided to stay together and announced plans to continue with a new vocalist. Several vocalists jammed with the three, including B-Real of Cypress Hill, but they did not want another rapper or anybody who sounded like de la Rocha. Contrary to popular belief, Layne Staley of Alice in Chains neither auditioned nor was asked to join the new project. Tom Morello denied this claim on his Twitter account in 2015. Music producer and friend Rick Rubin suggested that they play with Chris Cornell, the ex-frontman of Soundgarden. Rubin also persuaded the three of them to go into group therapy with performance coach Phil Towle after the breakup. Rubin was confident that with the right new voice, Rage Against the Machine had the potential to become a better band; he believed "it could turn into a Yardbirds-into-Led Zeppelin scenario." Commerford later credited Rubin for being the catalyst that brought Audioslave together. He called him "the angel at the crossroads" because "if it wasn't for him, I wouldn't be here today."The chemistry between Cornell and the other three was immediately apparent; as Morello described: "He stepped to the microphone and sang the song and I couldn't believe it. It didn't just sound good. It didn't sound great. It sounded transcendent. And...when there is an irreplaceable chemistry from the first moment, you can't deny it." The quartet wrote 21 songs during 19 days of rehearsal, and began working in the studio in late May 2001 with Rubin as producer, while sorting out the label and management issues.  answer the following question:  What is the name of the quartet that wrote 21 songs during 19 days of rehearsal?
A:
Audioslave