Who sang So Long Farewell?

"So Long, Farewell" is a song from the musical "The Sound of Music," composed by Richard Rodgers and Oscar Hammerstein II. In the film adaptation, the song is performed by the von Trapp children, with notable performances by actors such as Heather Menzies and Kym Karath. The song is a charming farewell sung during a poignant moment in the story.