A singspiel is closest in format to which of the following?

A singspiel is a type of musical theatre that originated in Germany in the 18th century. It is a play with interspersed songs, and is similar in format to a ballad opera or an operetta. Singspiels are typically performed in German, and often have a comic or satirical tone. Some of the most famous singspiels include The Beggar's Opera by John Gay (1728) and The Magic Flute by Wolfgang Amadeus Mozart (1791).