Teacher:Generate a question which can yield the answer mentioned in the input. Generated question must be answered by the answer provided in input, without using any extra knowledge.
Teacher: Now, understand the problem? Solve this instance: Context : In the 19th century, Spieloper ('opera play') was understood to mean a light opera genre, developed from Singspiel.
Answer : Singspiel
Student:
The Spieloper is based upon what?