What effect does the dwarves' song in Chapter 1 have on the plot of The Hobbit?

It creates exposition that provides background information about the dwarves' mission.

It creates a complicating incident by describing the generations-old feud between the dwarves and Bilbo's ancestors.

It is a turning pont in the story when Bilbo realizes he has no choice but to help the dwarves on their mission.

It sets up the rising action as the song describes the dangers ahead and pulls Bilbo into the mission.