Question: What charity single did Taylor Swift perform in Glendale, Arizona on her fourth concert tour?

Context paragraphs:
Fearless Tour: The Fearless Tour was the debut concert tour by American singer-songwriter Taylor Swift.  Also referred to as the Fearless Tour 2009 and the Fearless Tour 2010, it was launched in support of her second studio album ""Fearless"" (2008).  On the tour, she was joined by guests Kellie Pickler and Gloriana.  Teen singer Justin Bieber joined her as an opening act for the tour when she went to England in November 2009.  During the tour, Swift performed with guests such as John Mayer, Katy Perry, and Faith Hill.  It grossed $63,705,590 from 89 reported shows and an audience of 1,138,977.

Our Song (Taylor Swift song): "Our Song" is a country song performed by American singer-songwriter Taylor Swift.  The song was written by Swift and produced by Nathan Chapman.  It was released on September 9, 2007 by Big Machine Records as the third single from Swift's eponymous debut album, "Taylor Swift" (2006).  Swift solely composed "Our Song" for the talent show of her freshman year in high school, about a boyfriend who she did not have a song with.  It was included on "Taylor Swift" as she recalled its popularity with her classmates.  The uptempo track is musically driven mainly by banjo and lyrically describes a young couple who use the events in their lives in place of a regular song.

Speak Now World Tour: The Speak Now World Tour was the second concert tour by American singer-songwriter Taylor Swift.  Also referred to as the Speak Now World Tour 2011 and the Speak Now World Tour 2012, the tour was launched in support of her third studio album "Speak Now" (2010).  The tour visited Asia, Europe, North America, and Oceania.  It was ranked 10th in Pollstar's "Top 50 Worldwide Tour (Mid-Year)", earning over $40 million.  At the conclusion of 2011, the tour was placed fourth on Pollstar's annual "Top 25 Worldwide Tours", earning $104.2 million with 100 shows.  This made it the highest-grossing female and solo tour of 2011.

Ahoi Tour: Ahoi Tour was the fourth concert tour by German Industrial Metal band Rammstein, in support of their fourth studio album "Reise, Reise".  This was Rammstein last tour until the release of their sixth album Liebe ist für alle da.  The tour started in Berlin, Germany on October 11, 2004 and was due to end in Bogotá, Colombia on October 22, 2005 (6 days from the release of Rammstein's fifth studio album, Rosenrot) but the tour was cut short due to lead singer Till Lindemann being accidentally injured by keyboardist Christian "Flake" Lorenz during the Göteborg, Sweden concert on July 30, 2005.  The supporting acts for this tour were Exilia (2004), Apocalyptica (February 1, 2005 to February 28, 2005), AqME (AqME stood in for Apocalyptica on February 12, 2005 concert), Devil Sold His Soul (was due to play July 14–18 but dropped out), and Torgull (July 23, 2005).

Ronan (song): "Ronan" is a charity single released on September 8, 2012, by American singer Taylor Swift to the iTunes Store.  Swift's lyrics are based on a blog she read about a four-year-old boy, Ronan Thompson, who died from neuroblastoma in 2011.  Swift wrote the song by putting together quotes from blog creator Maya Thompson, Ronan's mother.  Thompson is credited as a co-writer of the song.  Swift first performed the song live for Stand Up to Cancer in September 2012, and has only performed it publicly one other time, at the Glendale, Arizona stop of The 1989 World Tour, at which Thompson was in attendance.  All proceeds from sales of the single go to help fight cancer.

The Great Unknown Tour: The Great Unknown Tour is the fourth concert tour by American recording artist, Rob Thomas.  Beginning June 2015, the tour will support his third studio album, "The Great Unknown".  The tour will predominately perform in the United States and Canada, with performances in theaters and amphitheaters.  Thomas will also perform at music festivals during the summer.

The 1989 World Tour: The 1989 World Tour was the fourth concert tour by American singer-songwriter Taylor Swift, in support of her fifth studio album, "1989" (2014).  The tour's European and North American dates, as well as two shows in Japan, were announced in November 2014, followed by the Oceania dates in December 2014.  Additional dates for Singapore and Shanghai were announced in June 2015 with a third and final Melbourne show announced in July 2015.  The tour began on May 5, 2015, in Tokyo, Japan and concluded on December 12, 2015 in Melbourne, Australia, the day before her 26th birthday.  The tour became Swift's highest grossing and most attended tour to date, mobilizing 2,278,647 fans and $250,733,097 revenue.  It was the highest grossing tour in the world in 2015.

Picture to Burn: "Picture to Burn" is a song recorded by American singer-songwriter Taylor Swift.  It was co-written by Swift and Liz Rose, and produced by Nathan Chapman.  It was released on February 3, 2008 by Big Machine Records as the fourth single from Swift's eponymous studio album, "Taylor Swift" (2006).  It was inspired by the narcissistic and cocky nature of her former high school classmate and ex-boyfriend Jordan Alford with whom Swift never established a formal relationship.  In retrospect, Swift has stated that she has evolved on a personal level and as a songwriter, claiming she processed emotions differently since "Picture to Burn".  The song was chosen as a single based on the audience's reaction to it in concert.  Musically, the track is of the country rock genre with prominent usage of guitar, banjo, and drums.  The lyrics concern setting fire to photographs of a former boyfriend.

The Taylor Swift Holiday Collection: The Taylor Swift Holiday Collection, originally titled Sounds of the Season: The Taylor Swift Holiday Collection, is a Christmas EP by American singer Taylor Swift.  The EP was first released on October 14, 2007 by Big Machine Records exclusively to Target stores in the United States and online.  The release was originally a limited release for the 2007 holiday season, but was re-released to iTunes and Amazon.com on December 2, 2008 and again in October 2009 to Target stores.  "The Taylor Swift Holiday Collection" features cover versions of Christmas songs and two original tracks written by Swift, "Christmases When You Were Mine" and "Christmas Must Be Something More", all of which have a country pop sound.

Viva la Vida Tour: The Viva la Vida Tour was the fourth concert tour by British band Coldplay.  The tour was in support their fourth studio album "Viva la Vida or Death and All His Friends" (2008).  The tour was a massive commercial and critical success visiting Europe, Asia, the Americas and Australasia.  The tour further established the band as one the concert industry's biggest draws and as one of the world's most popular bands.  According to Pollstar from 2008 to 2010, the tour grossed $209.4 million

Supporting paragraphs: Ronan (song) The 1989 World Tour
Answer: Ronan