Question: Deekay wrote for what South Korean girl group formed by S.M. Entertainment?

Context paragraphs:
The Grace (band): The Grace () is a South Korean girl group formed by S.M. Entertainment in 2005.  The group originally consists of four members: Lina, Dana, Sunday and Stephanie.  Member Stephanie officially departed from the group in 2016 after her contract expired.

Jessica Jung: Jessica Jung (born April 18, 1989), known professionally as Jessica, is an American singer, songwriter, actress, model, fashion designer, and businesswoman currently based in South Korea.  Jung was born and raised in San Francisco, California.  At the age of eleven, she was discovered by South Korean entertainment agency S.M. Entertainment and subsequently moved to South Korea.  In 2007, Jung debuted as a member of the South Korean girl group Girls' Generation.  The group later became one of the best-selling artists in South Korea, and one of South Korea's most popular girl groups nationwide and worldwide.

Krystal Jung: Chrystal Soo Jung (born October 24, 1994), better known by the mononym Krystal, is an American singer and actress based in South Korea.  She debuted in 2009 as a member of South Korean girl group f(x) and has further participated in S.M. Entertainment's project group S.M.  The Ballad.  Aside from group activities, she has also participated in various television dramas such as "" (2011–12), "The Heirs" (2013), "My Lovely Girl" (2014), and "The Bride of Habaek" (2017).

Pink Tape: Pink Tape is the second studio album by South Korean girl group f(x).  The album was released on July 29, 2013 by S.M. Entertainment.  "Pink Tape" is the first studio album by f(x) in over two years, the last being the repackage of their first album "Hot Summer" in 2011, and the first Korean release in over a year since 2012's "Electric Shock".  The album peaked at the number one position on multiple music charts internationally including Billboard's World Albums and South Korea's Gaon charts.  "Billboard" named "Rum Pum Pum Pum" #59 on their list of 100 Greatest Girl Group Songs of All Time.

Mr.Mr. (EP): Mr.Mr.  is the fourth extended play (EP) by South Korean girl group Girls' Generation.  The EP consists of six tracks and it incorporates electropop and R&B-pop music genres.  It was released for digital download by S.M. Entertainment and KT Music on February 24, 2014.  The CD and digital version were released in Hong Kong on the same day, and was made available for purchase on February 27 in South Korea.  To promote the album, Girls' Generation appeared on several South Korean music programs including "Music Bank" and "Inkigayo".  The title track was released as a single.  This is the final Korean EP featuring member Jessica.

Girls' Generation: Girls' Generation (), also known as SNSD, is a South Korean girl group formed by S.M. Entertainment.  The group is composed of eight members: Taeyeon, Sunny, Tiffany, Hyoyeon, Yuri, Sooyoung, Yoona, and Seohyun.  Originally a nine-piece group (with Jessica, who later departed from the group in September 2014), Girls' Generation debuted in 2007 with their Korean eponymous debut album.  Though the album gained some attention, it was not until 2009 that the group rose to fame with the single "Gee", which claimed the top spot on KBS's "Music Bank" for a record-breaking nine consecutive weeks and was named the most popular song of the 2000s in South Korea by Melon.  Girls' Generation further consolidated their popularity on the South Korean music scene with follow-up singles "Tell Me Your Wish (Genie)", "Oh! ", and "Run Devil Run", which were released in mid-2009 and early 2010.

Red Velvet (band): Red Velvet (Hangul: 레드벨벳) is a South Korean girl group formed by S.M. Entertainment.  The group debuted on August 1, 2014, with their digital single "Happiness" and with four members: Irene, Seulgi, Wendy and Joy.  In March 2015, Red Velvet added a fifth member, Yeri, to the group.

Park Hee-von: Park Hee-von (born Park Jae-young on May 11, 1983) is a South Korean actress.  Park Jae-young made her entertainment debut in 2001 as a member of the South Korean girl group M.I.L.K under S.M. Entertainment.  M.I.L.K (which stood for "Made in Lovely Kin") released one album titled "With Freshness", then disbanded two years later.  When Park shifted careers from singing to acting, she began using the stage name Park Hee-von.  Park became best known for starring in independent films and cable TV series.

Deekay: Deekay is a Danish production and songwriting team founded by Lars Halvor Jensen, Martin Michael Larsson with other members Tim "Data" McEwan, Daniel "Obi" Klein and Johannes "Josh" Jørgensen.  The name Deekay comes from the acronym dk, which means Denmark.  Deekay have written and produced for artists like Jason Derulo, Jordin Sparks, Lil Wayne, Diddy, Sugababes, Orianthi, JLS, Tinie Tempah, Charice, Allison Iraheta, Method Man, Fat Joe, Styles P, Lemar, Medina, Girls' Generation, Red Velvet, LOOΠΔ, EXO and others.

I Just Wanna Dance: I Just Wanna Dance is the debut extended play by South Korea-based American singer Tiffany.  It was released by S.M. Entertainment on May 11, 2016.  Lee Soo-man, former president of S.M. Entertainment, served as executive producer on the EP.  The EP marked the official solo debut of Tiffany after having been known as a member of South Korean girl group Girls' Generation for nearly nine years.  Musically, the record is a primarily synthpop album with elements of trap and R&B that draws heavy influence from American female artists of the 1990s.

Supporting paragraphs: Deekay Red Velvet (band)
Answer: Red Velvet