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.