Who did darcy say was responsible for elizabeth's acceptance of his marriage proposal?

Lady Catherine De Bourgh

In Jane Austen's Pride and Prejudice, Darcy proposes to Elizabeth twice. The first time Elizabeth rejected Darcy and called him the last man she would ever marry. The second time, however, Elizabeth changed heart and accepted Darcy. Darcy told Elizabeth that his second proposal was because of Lady Catherine De Bourgh who told him of Elizabeth's impertinence and refusal to promise never to become engaged to Darcy. Darcy decided he still has hope for marriage with Elizabeth hearing that she may still care for him.