Answer:
The interaction from Nora and the Nurse in Act One.
Despite the fact that they have been together for a long time, Nora appears to be the first to inquire about the nurse's history. She's starting to notice society and express an interest in other people. She's also conscious of her own frailty.
Mrs. Linde's assertion that Nora has never known hard labor causes Nora to confess her secret of saving Torvald's life by obtaining the money for their journey overseas.