Question: Haseul is the third single album by the girl group that was formed by which subsidiary of Polaris Entertainment?

Context paragraphs:
Code 02 Pretty Pretty: Code#02 Pretty Pretty is the second extended play by South Korean girl group Ladies' Code.  It was released on September 6, 2013 through Polaris Entertainment and CJ E&M Music.  The album was well promoted with three singles.  The lead single "Hate You" was released on August 6, 2013.  The title track "Pretty Pretty" was released as the second single on September 6, 2013 along with the album.  The third and final single "I'm Fine Thank You" was released on September 15, 2014 as the tribute to members EunB and RiSe who died in a fatal car accident in early September 2014.

Muses Diary: Muses Diary is the debut single album recorded by South Korean girl group Nine Muses A, a sub-group from girl group Nine Muses.  The single album was released as a digital download on August 4, 2016 by Star Empire Entertainment and distributed by KT Music, and as a physical album on August 8.  The title track is "Lip 2 Lip" and was written and composed by Jung Changwook.  The single has two B-sides, "Shh!"  and "Monster".

Code 01 Bad Girl: Code#01 Bad Girl (Korean: Code#01 나쁜여자 ) is the debut extended play by South Korean girl group Ladies' Code.  It was released on March 7, 2013 through Polaris Entertainment and CJ E&M Music.  Its lead single "Bad Girl" was released the same day.

Ladies' Code: Ladies' Code (Korean: 레이디스 코드 ) is a South Korean girl group formed by Polaris Entertainment in 2013.  The group's original lineup consisted of leader Ashley and members RiSe, EunB, Sojung, and Zuny.  They made their debut with the mini-album "Code#01" and the lead track "Bad Girl", which were released on March 7, 2013.  On September 3, 2014, the group was involved in a car accident that resulted in the deaths of EunB and RiSe.  Ladies' Code returned as a trio in February 2016 with the extended play "Myst3ry".  In October 2016, they issued "The Rain" from their new mini album "Strang3r".

Kiss Kiss (Ladies' Code song): "Kiss Kiss" (Korean: 키스 키스 ) is a song by South Korean girl group Ladies' Code.  It was released as a single album on August 7, 2014 by Polaris Entertainment and is the group's fifth single overall.  This was the last release featuring members EunB and RiSe, after their death on September 2014.

Haseul (single): HaSeul (or LOOΠΔ & HaSeul) is the third single album from South Korean girl group Loona's pre-debut project.  It was released on December 15, 2016, by Blockberry Creative and distributed by CJ E&M.  It introduces member HaSeul and contains two tracks, her solo "Let Me In", and a Christmas collaboration song between her, HeeJin and HyunJin, titled "The Carol".  Music Videos for both songs were released simultaneously on December 15.

So Wonderful (Ladies' Code song): "So Wonderful" is a song by South Korean girl group Ladies' Code.  It was released as a digital single on February 13, 2014 by Polaris Entertainment.  It is one of the best charting songs they've released to date, with its peak position being 18 on the Billboard Hot 100 K-pop songs, the other one of their higher charting songs was "Hate You".  The song is performed in Korean, apart from the English title.

Yeojin (single): YeoJin (also known as LOOΠΔ & YeoJin or HaSeul & YeoJin) is the fourth single album from South Korean girl group Loona's pre-debut project.  It was released on January 16, 2017, by Blockberry Creative and distributed by CJ E&M.  It introduces member YeoJin and contains three tracks, her solo "Kiss Later", a duet between HeeJin and HyunJin titled "My Sunday", and a duet between her and HaSeul titled "My Melody".  Music Videos for each song were released once a day from January 16 to the 18.

Loona (band): Loona, stylized as LOOΠΔ, is an upcoming South Korean girl group formed by Blockberry Creative, a subsidiary of Polaris Entertainment, set to debut in 2018.  Each month, starting in October 2016 and lasting for 18 months, there is a new release of a single album or extended play, introducing a new member or sub-unit to the group.  In 2018, with the project completed, all twelve members will debut as one group.

ViVi (single): ViVi (or HaSeul & ViVi) is the fifth single album from South Korean girl group Loona's pre-debut project.  It was released on April 17, 2017, by Blockberry Creative and distributed by CJ E&M.  It is the first solo single by member ViVi who was previously introduced as a member of Loona 1/3, and contains two tracks, "Everyday I Love You", featuring previously revealed member HaSeul, and "Everyday I Need You", featuring at-time upcoming Loona member JinSoul.

Supporting paragraphs: Haseul (single) Loona (band)
Answer: Blockberry Creative