question: Which opera has more acts, Riders to the Sea or Lucio Silla?
answer: Lucio Silla
context: Title: Milanese Quartets (Mozart)
  Passage: The six string quartets, K. 155–160, were composed by Wolfgang Amadeus Mozart in late 1772 and early 1773.  Because they were composed in Milan while he was working on his opera Lucio Silla, they are popularly known as the Milanese Quartets.  Before this set was composed, Mozart had written one earlier string quartet (K. 80/73f in 1770), so these six quartets are ordinally numbered from No. 2 to No. 7.  The quartets are written in a plan of keys of D-G-C-F-B♭ -E♭ following the circle of fifths.
  Title: Lucio Silla
  Passage: Lucio Silla (pronounced , ] ), K. 135, is an Italian opera in three acts composed by Wolfgang Amadeus Mozart.  The libretto was written by Giovanni de Gamerra.
  Title: Riders to the Sea (opera)
  Passage: Riders to the Sea is a short one-act opera by Ralph Vaughan Williams, based on the play of the same name by John Millington Synge.  The composer completed the score in 1927, but it was not premiered until 1 December 1937, at the Royal College of Music, London.  The opera remained largely the province of students and amateurs until it entered the repertoire of Sadler's Wells in 1953.
  Title: Silla (opera)
  Passage: Silla (full title "Lucio Cornelio Silla", HWV 10) is an opera seria (referred to as a "dramma per musica") in three acts by George Frideric Handel.  The Italian-language libretto was by Giacomo Rossi.  The story concerns the Roman dictator Lucius Cornelius Sulla (138–78 BC) as recounted by Plutarch.
  Title: Jang Bogo
  Passage: Jang Bogo (787–846), childhood name: Gungbok, was a Sillan who rose to prominence in the Later Silla period of Korea as a powerful maritime figure who effectively controlled the Yellow Sea (West Sea), and dominated the trade between Silla, Heian Japan, and Tang China for decades.  His impressive fleet of ships was centered in Wando, an island in South Jeolla Province.  So influential a figure did Jang become in late Silla politics that he was granted official office as Maritime Commissioner of the Cheonghaejin Garrison (on Wando) and came near to marrying his daughter into the Silla Royal House before his assassination in 846.  He was worshipped as a god following his death.
citations: Riders to the Sea (opera) Lucio Silla