Answer: They went blind by getting there eyes pecked out.
Ashputtle is a story by the brothers Grimm. The adaptation, known as "Cinderella" is the more famous version nowadays. In the story, Ashputtle also loses a shoe and the prince identifies her by seeing how well it fits her. However, the two evil stepsisters meet with a different fate. On their way to Ashputtle's wedding, their eyes are pecked out by pigeons, leaving them permanently blind.
To tell a narrative story, you should be the one telling a story of something that you have experienced. I'm sure that if there was an option that states first or third person omniscient, then my answer would be differnet. But based on the context, i believe this is the correct answer
