Which of the following is true about the études? it was based around a dance of polish origin. études are composed of three sets of studies for solo piano, with 27 pieces in total. études consists of 21 short pieces for solo piano. études use of the right hand to create a song-like melody.

If you are referring to Chopin's Etudes, then the correct answer is the second option - Études are composed of three sets of studies for solo piano, with 27 pieces in total.
Chopin composed three sets of etudes for solo piano - the first one consists of 12, the second one also 12, and the last one consists of 3 etudes. Each of these sets was dedicated to someone - the first one to Liszt, the second one to his mistress Marie d'Agoult, and the third one to various people.