Read this text trailer about the story of Cinderella.

Cinderella faces a difficult life in the home of her evil stepmother. Forced to do chores day in and day out, she longs for the carefree existence of her stepsisters. When the prince announces a ball, Cinderella longs to go, but her stepmother forbids it. However, a stranger helps Cinderella in a very unexpected way.

What is the tone of this trailer?

formal
informal
humorous
mysterious