The sentence that best describes the author's purpose for writing is
The author wrote this story to explain the capabilities of the crab represented in this story as Pau Amma. He could do a lot of things as seen at the end of the excerpt.
This was despite the fact that Pau Amma was disobedient to the creator who assigned the animals their roles. He also caused a lot of mischief by causing an overflow of water from the sea. In the end, he did not lose much as he still had a lot of abilities.
Learn more about Pau Amma here:
https://brainly.com/question/11833427