You will be given a definition of a task first, then some input of the task.
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.

Context : Ragnarok DS, known in Japan as Ragnarok Online DS (DS), is a Nintendo DS video game based on the MMORPG Ragnarok Online and was released in Japan on December 18, 2008.
Answer : Ragnarok Online
Output:
What series is Ragnarok DS part of?