Question: In Frozen Fever, a short animated sequel to the hit movie, Queen Elsa of Arendelle organizes a party to celebrate whose birthday?

Context articles: Annika Herlitz
Let It Go (Disney song)
Half-birthday
Frozen Fever
Making Today a Perfect Day
Frozen Ever After
For the First Time in Forever
Anna Faith
Elsa (Disney)
Ravi Agrawal (Film Producer)

Annika Herlitz, (born 22 September 1984) is a Swedish singer, musical performer, and voice actress.
 She provided the Swedish voice for the snow queen Elsa in the Walt Disney film Frozen.
 The film was released in Sweden on 31 January 2014.
 Herlitz performed the song from Frozen Let It Go at Allsång på Skansen.
"Let It Go" is a song from Disney's 2013 animated feature film "Frozen", whose music and lyrics were composed by husband-and-wife songwriting team Kristen Anderson-Lopez and Robert Lopez.
 The song was performed in its original show-tune version in the film by American actress and singer Idina Menzel in her vocal role as Queen Elsa.
 Anderson-Lopez and Lopez also composed a simplified pop version (with shorter lyrics and background chorus) which was performed by actress and singer Demi Lovato over the start of the film's closing credits.
 A music video was separately released for the pop version.
A half-birthday is a day approximately six months before or after the anniversary of a person's birth.
 It is sometimes marked by people whose birthday falls near major holidays, the celebration of which may overshadow celebration of the birthday.
 It may also be marked by students whose birthday does not occur during the regular school year; a half-birthday allows a celebration with friends at school, with half a cake.
Frozen Fever is a 2015 American computer-animated musical fantasy short film produced by Walt Disney Animation Studios and released by Walt Disney Pictures.
 It is a sequel to the 2013 feature film "Frozen", and tells the story of Anna's birthday party given by Elsa with the help of Kristoff, Sven, and Olaf.
 Chris Buck and Jennifer Lee again served as the directors with Kristen Bell, Idina Menzel, Jonathan Groff, and Josh Gad providing the lead voices.
"Making Today a Perfect Day" is a song from the 2015 Walt Disney Animation Studios computer-animated short film "Frozen Fever", with music and lyrics by Kristen Anderson-Lopez and Robert Lopez and performed throughout most of the short.
 It was released as a single in the United States on March 12, 2015.
Frozen Ever After is a dark water ride attraction in Epcot at the Walt Disney World Resort.
 Part of the Norway Pavilion of the park's World Showcase section, the attraction features scenes inspired by Disney's 2013 animated film "Frozen" as well as the 2015 animated short "Frozen Fever".
 It opened on June 21, 2016 and replaced the former Maelstrom attraction, utilizing the same ride vehicles and a similar track layout.
"For the First Time in Forever" is a song from Disney's 2013 animated feature film "Frozen", with music and lyrics composed by Kristen Anderson-Lopez and Robert Lopez.
 It is reprised later in the musical.
 Both versions are sung by sisters Princess Anna (Kristen Bell) and Queen Elsa (Idina Menzel).
Anna Faith Carlson (born November 21, 1995) is an Instagram model and cosplayer from Florida.
 She is best known for impersonating the character of Queen Elsa from the Disney animated film "Frozen".
Queen Elsa of Arendelle is a fictional character who appears in Walt Disney Animation Studios' 53rd animated film "Frozen".
 She is voiced primarily by Broadway actress and singer Idina Menzel.
 At the beginning of the film, she is voiced by Eva Bella as a young child and by Spencer Lacey Ganus as a teenager.
Ravi Agrawal is a Hindi film Producer, Entrepreneur, and a book publisher.
 He has already produced the Bollywood films like Fever, Radio – Love on Air, and Handover.
 He is known to be the producer of the thriller movies.
 Most of the movies like Fever, Deadline: Sirf 24 Ghante, and Handover were the hit movie he had produced.
 While unfortunately Radio – Love On Air movie haven't marched to success.