Question: Which opera has more acts, Der Zwerg or Billy Budd?
Context: Hervey Alan (22 February 1910 – 12 January 1982) was an English operatic bass and voice teacher.  During his career he sang leading roles with most of Great Britain's major opera institutions, including the Edinburgh Festival, the Glyndebourne Festival, the Royal Opera House, the Sadler's Wells Opera, and the Welsh National Opera.  He is best known for creating the role of Mr. Redburn in the world premiere of Benjamin Britten's "Billy Budd" at the Royal Opera House, London, on 1 December 1951.  Music critic Elizabeth Forbes wrote that his voice was "dark toned, resonant", and "especially effective as Zaccaria in "Nabucco". Der Zwerg ("The Dwarf"), Op.  17, is an opera in one act by Austrian composer Alexander von Zemlinsky to a libretto by Georg Klaren, freely adapted from the short story "The Birthday of the Infanta" by Oscar Wilde. Billy Budd is a 1962 CinemaScope film produced, directed, and co-written by Peter Ustinov.  Adapted from the stage play version of Herman Melville's short novel "Billy Budd", it starred Terence Stamp as Billy Budd, Robert Ryan as John Claggart, and Ustinov as Captain Vere.  In his film debut, Stamp was nominated for an Academy Award for Best Supporting Actor, and received a Golden Globe Award for Most Promising Male Newcomer.  The film was nominated for four BAFTAs. Nigel Levings is an Australian stage lighting designer.  He has designed lights for over 400 productions.  He works extensively on operas, and has designed a large portion of Opera Australia's repertoire.  Some of his most significant works include operas such as "The Demon" at the Bregenz Festival and for Zurich Opera; "Billy Budd" for the Welsh National Opera, Opera Australia, Canadian Opera Company, and for the English National Opera; "Nabucco" for Opera Australia; "Wozzeck" for Opera Australia; "L'Orfeo" for Innsbrucker Festwochen der Alten Musik and the Berlin State Opera; "A Midsummer Night's Dream" for the 1994 Edinburgh Festival; "La Belle Vivette" for the English National Opera; "Simon Boccanegra" for the Royal Opera House, Washington National Opera, and Dallas Opera; "Falstaff" for Théâtre du Châtelet; "Idomeneo", "Turandot", and "The Barber of Seville" for the Houston Grand Opera; and "Queen of Spades" for the Dallas Opera. Rodney Gilfry is a leading American opera baritone.  After launching his career at Frankfurt Opera in 1987, Gilfry quickly established a reputation for stylish singing and acting.  A renowned Mozart specialist, he has given acclaimed performances as Don Giovanni, Count Almaviva, Guglielmo, and Papageno, and is also known for his work in rôles from the standard baritone repertoire (Pelleas, Valentin, Orestes, Belcore, Billy Budd). John Socman is an opera in three acts by George Lloyd to a libretto by William Lloyd (the composer’s father).  It was first performed by the Carl Rosa Opera Company at the Bristol Hippodrome, England on 15 May 1951.  The work was one of three operatic commissions to mark the Festival of Britain (the others being "The Pilgrim’s Progress" and "Billy Budd"). Robert Nagy (March 3, 1929 – November 7, 2008) was an American operatic tenor who had a lengthy and fruitful association with the Metropolitan Opera that lasted for three decades.  His association with the Met began when he won the Metropolitan Opera National Council Auditions in 1956.  He mostly portrayed comprimario roles at the Met where his most memorable early role was the Messenger in "Aida"; a role he sang 172 times for the company.  He notably sang in the world premieres of two operas by Samuel Barber at the Met: "Vanessa" (1958) and "Antony and Cleopatra" (1966).  He also sang in the company premieres of "Die Frau ohne Schatten" (1966), "Billy Budd" (1978) and "L'enfant et les sortilèges" (1981).  Although Nagy specialized in supporting roles, he also portrayed several leading parts at the Met, among them Florestan in "Fidelio", Herodes in "Salome", and the Drum Major in "Wozzeck'.  He remained on the Met roster through the end of the 1987–88 season, performing 1,187 performances with the Met during his thirty years with the company. Billy Budd, Op. 50, is an opera by Benjamin Britten to a libretto by the English novelist E. M. Forster and Eric Crozier, based on the short novel "Billy Budd" by Herman Melville.  Originally in four acts, it was first performed at the Royal Opera House, London, on 1 December 1951; it was later revised as a two-act opera with a prologue and an epilogue. Ronald Lewis (16 January 1916 – 30 December 1967) was a Welsh opera singer who sang leading baritone roles at the Royal Opera House, where he was a Principal Baritone in the company from 1951 to 1967, and the Welsh National Opera.  He created the roles of Jean in Arthur Bliss's "The Olympians", Bosun in Benjamin Britten's "Billy Budd", and Henry Cuffe in Britten's "Gloriana". Der Zwerg (The Dwarf) is a lied (or ballad) for voice and piano by Franz Schubert, written in the mid-1820s on a text by Matthäus von Collin.  In Otto Erich Deutsch's catalogue of Schubert's works, it is Op. 22, No. 1, D. 771.
Answer: Billy Budd, Op. 50, is an opera by Benjamin Britten to a libretto by the English novelist E. M. Forster and Eric Crozier, based on the short novel "Billy Budd" by Herman Melville. Originally in four acts, it was first performed at the Royal Opera House, London, on 1 December 1951; it was later revised as a two-act opera with a prologue and an epilogue.