Final answer:
Elizabeth Bennet's opinion of Mr. Darcy changes at Pemberley as she admires his estate, hears positive accounts of his character from the housekeeper, and experiences his civil demeanor first-hand.
Step-by-step explanation:
At Pemberley, Elizabeth Bennet's mind about Mr. Darcy begins to change due to a combination of factors. Firstly, she is impressed by the beauty and good management of his estate, which speaks to his character as a responsible and capable individual. Furthermore, Elizabeth's interactions with the housekeeper, who speaks highly of Darcy, as well as the unexpected, gentlemanly manner in which Darcy himself greets her and her relatives, contribute to her reassessment of him. Seeing Darcy in his own environment, where he is both respected and respectful, helps Elizabeth realize that her initial prejudices against him may have been unfounded, and allows her to see him in a new light.