Question: Which opera is by Christoph Willibald Gluck, Iphigénie en Tauride or Der Barbier von Bagdad?
Context: Styled a "festa teatrale", "Le feste d'Apollo" consists of a prologue and three self-contained acts on the model of French "opéra-ballet" (the court of Parma was passionately interested in French culture).  Gluck knew the Archduchess Maria Amalia well as she had sung in two of his operas, "Il Parnaso confuso" and "La corona", in Vienna.  The composer recycled a lot of music from his earlier operas in the score of "Le feste".  In fact, the whole of the third act, "Orfeo", is a shorter reworking of his most famous piece, "Orfeo ed Euridice" (1762).  The overture to the prologue is taken from "Telemaco".  Gluck later reused some of the choruses in two of the operas he wrote for Paris, "Iphigénie en Aulide" and "Iphigénie en Tauride". Der Barbier von Bagdad ("The Barber of Baghdad") is a comic opera in two acts by Peter Cornelius to a German libretto by the composer, based on "The Tale of the Tailor" and "The Barber’s Stories of his Six Brothers" in "One Thousand and One Nights".  The first of three operas by Cornelius, the piece was first performed at the Hoftheater in Weimar on 15 December 1858. Iphigénie en Aulide ("Iphigeneia in Aulis") is an opera in three acts by Christoph Willibald Gluck, the first work he wrote for the Paris stage.  The libretto was written by François-Louis Gand Le Bland Du Roullet and was based on Jean Racine's tragedy "Iphigénie".  It was premiered on 19 April 1774 by the Paris Opéra in the second Salle du Palais-Royal and revived in a slightly revised version the following year. Nicolas-François Guillard (16 January 1752 – 26 December 1814) was a French librettist.  He was born in Chartres and died in Paris, the recipient of a government pension in recognition of his work writing librettos.  He was also on "Comité de Lecture" of the Paris Opéra.  One of the foremost of the French librettist of his generation, he wrote libretti for many noted composers of the day, including Salieri ("Les Horaces") and in particular Sacchini ("Oedipe à Colone", amongst many others).  His most famous work is "Iphigénie en Tauride", his first libretto, set by Gluck after the composer had initially rejected it.  Gluck collaborated with Guillard to heavily recast the libretto, not only to suit Gluck's artistic preferences, but also to accommodate pre-existing music that Gluck borrowed, both from himself and from other composers, when composing the opera. Iphigénie en Tauride ("Iphigeneia in Tauris") is a tragédie lyrique in four acts by Niccolò Piccinni, which was first performed on 23 January 1781 by the Académie royale de musique (the Paris Opéra) in the second Salle du Palais-Royal.  The opera's libretto, by Alphonse du Congé Dubreuil, is based on a play of the same name by Claude Guimond de La Touche, although the ultimate source was the tragedy "Iphigeneia in Tauris" by Euripides. Iphigénie en Tauride ("Iphigenia in Tauris") is a 1779 opera by Christoph Willibald Gluck in four acts.  It was his fifth opera for the French stage.  The libretto was written by Nicolas-François Guillard. This is a discography of Iphigénie en Tauride, an opera by Christoph Willibald Gluck, first performed at the Paris Opéra on May 18, 1779. Magdaléna Hajóssyová (born 25 July 1946, Bratislava) is a classical Slovak soprano who has had an active international career singing in operas, concerts, and recitals since the late 1960s.  She has been particularly active at the Prague State Opera where she has been a principal artist since 1972.  She has also had a long and fruitful partnership with the Berlin State Opera beginning in 1975.  In 1977, 1981, and 1987, she won the Berlin Critic's Prize for her portrayal of the roles of Margarete in Charles Gounod's "Faust", the Elektra in Mozart's "Idomeneo", Carl Maria von Weber's "Euryanthe", and Christoph Willibald Gluck's "Iphigénie en Aulide". Iphigénie en Tauride (English: "Iphigeneia in Tauris") is an opera by the French composers Henri Desmarets and André Campra.  It takes the form of a "tragédie en musique" in a prologue and five acts.  The libretto is by Joseph-François Duché de Vancy with additions by Antoine Danchet.  Desmarets had begun work on the opera around 1696 but abandoned it when he was forced to go into exile in 1699.  Campra and his regular librettist Danchet took up the piece and wrote the prologue, most of Act Five, two arias in Act One, an aria for Acts Two and Three, and two arias for the fourth act.  The plot is ultimately based on Euripides' tragedy "Iphigeneia in Tauris". Marie-Louise Desmatins (fl.  1682–1708) was a French soprano and creator of many roles in French Baroque opera.  She performed in Jean Baptiste Lully's "Persée" (1682), "Armide" (1686 and 1703 revival), "Achille et Polyxène" (1687), "Thésée" (1698 revival), "Isis" (1704 revival), "Roland" (1705 revival), "Bellérophon" (1705 revival), "Alceste" (1706 revival), as well as in Pascal Collasse's "Enée et Lavinie" (1690) and "Thétis et Pélée" (1699 revival), André Cardinal Destouches' "Issé" (1697), Henri Desmarets' "Didon" (1704 revival), André Campra's "Iphigénie en Tauride" (1704), and Marin Marais' "Alcyone" (1706).
Answer: Iphigénie en Tauride