No improvement to this sentence is necessary. It makes perfect sense on its own and sounds right. "Either" always takes an "or" else the word wouldn't make sense, as it's meant to contrast binary options.
eg.
I'm either going to eat food or drink water.
Answer:
A. by inspiring Brayden to pick up his litter
Explanation:
The answer is A because after Bear sees his waste in the river he sees his wrongings and hides away in a cave eating like the average bear today. This inspires Brayden to pick up his litter to not be hurt or hurting others buy this wronging
A term for a story within a story would be called a frame story.
I hope this helps!