Q: In this task, you're given a story (which contains five sentences only). Your task is to find all the characters which are available in the given story.
Sentence1: My mom used to go sledding by her parent's cottage. Sentence2: They would bring the sled up these giant sand dunes that were frozen. Sentence3: They would slide down them, but one time they had the unexpected. Sentence4: They went too fast and went all the way down to the water. Sentence5: The lake wasn't completely frozen so they got soaking wet.
A:
I (myself), My mom's parents, My mom