In the City of Ember, What did Lina and Doon discover at the end of the upward, zig zag path from the river?

they discovered a new world that was very dark, but that had a bright light.

Explanation:

"City of Ember" tells the story of how the children Lina and Doon, after walking up a zigzag path from the river, found a new world. This world was below the earth, many kilometers away from the surface. Although it was very dark, the world was maintained by a silver light generator that was essential for the survival of the inhabitants of that place. However, this light generator threatens to stop working, which causes Lina and Doon to look for a way to prevent this from happening.

being untruthful

eating too much

overstaying one's welcom

this is that correct answer.