Answer is C: Mrs. Linde says that Krogstad would have done anything for her.
Explanation: Even though Nora advices Mrs. Linde not to go to Krogstad because she thinks this will be harmful for her, since they have had a romantic relationship in the past, Mrs. Linde decides to get together with him anyways, and her decision is evident because she asks Nora about where he lives. She still have feelings for Krogstad, and regrets leaving him to marry the wrong man.