Final answer:
Mathilde wants to leave the party because she is tired of pretending to be someone she isn't.
Step-by-step explanation:
The subject of this question is English, as it is asking about a character's motivation in a literary work.
The correct answer is B. she is tired of pretending to be someone she isn't. In the story, Mathilde is exhausted from maintaining appearances and wants to leave the party so she can be herself again.
Learn more about Character motivation in a literary work